phase3: nullfix.py batch script — bang/late/param-nullable

Automated null-safety fixes driven by dart analyze (no corruption): - unchecked_use_of_nullable_value: insert '!' on receiver (property/method/[]/op) - not_initialized field/var: mark 'late' - missing_default_value_for_parameter: nullable param Errors: 2374(peak) -> 907
2026-07-25 18:13:01 +08:00
parent 8f3d3509ea
commit fce670664b
99 changed files with 1013 additions and 838 deletions
--- a/lib/widgets/general/add_remove_button.dart
+++ b/lib/widgets/general/add_remove_button.dart
@@ -40,7 +40,7 @@ class AddRemoveButton extends StatefulWidget {
 }

 class AddRemoveButtonState extends State<AddRemoveButton> {
-  int _qty;
+  late int _qty;
  var zeroColor = const Color(0xFFEFEFEF);
  var qtyColor = const Color(0xFFFF6666);
  var zeroFontColor = const Color(0xFF888888);
@@ -48,7 +48,7 @@ class AddRemoveButtonState extends State<AddRemoveButton> {

  var d = 1;

-  CartInfo cartInfo;
+  late CartInfo cartInfo;

  GlobalKey startKey = GlobalKey();

@@ -63,10 +63,10 @@ class AddRemoveButtonState extends State<AddRemoveButton> {
      _qty = 0;
      cartInfo = Utils.getCartInfoByBusiness(store.state.cartInfos, widget.business);
      if (cartInfo != null) {
-        for (var i = 0; i < cartInfo.productList.length; i++) {
-          if (cartInfo.productList[i].product.id == widget.product.id
-              && cartInfo.productList[i].unitPrice == 0.0) {
-            _qty = cartInfo.productList[i].quantity.round();
+        for (var i = 0; i < cartInfo.productList!.length; i++) {
+          if (cartInfo.productList![i].product!.id == widget.product.id
+              && cartInfo.productList![i].unitPrice == 0.0) {
+            _qty = cartInfo.productList![i].quantity!.round();
            break;
          }
        }
@@ -78,7 +78,7 @@ class AddRemoveButtonState extends State<AddRemoveButton> {
        ),
      );
    }
-    if (widget.product.leftNum <= 0) {
+    if (widget.product.leftNum! <= 0) {
      return Container(
        padding: EdgeInsets.only(top: 0.0, bottom: 10.0, left: 8.0, right: 8.0),
        child: Text(
@@ -104,9 +104,9 @@ class AddRemoveButtonState extends State<AddRemoveButton> {
      _qty = 0;
      cartInfo = Utils.getCartInfoByBusiness(store.state.cartInfos, widget.business);
      if (cartInfo != null) {
-        for (var i = 0; i < cartInfo.productList.length; i++) {
-          if (cartInfo.productList[i].product.id == widget.product.id) {
-            _qty = cartInfo.productList[i].quantity.round();
+        for (var i = 0; i < cartInfo.productList!.length; i++) {
+          if (cartInfo.productList![i].product!.id == widget.product.id) {
+            _qty = cartInfo.productList![i].quantity!.round();
            break;
          }
        }
@@ -197,15 +197,15 @@ class AddRemoveButtonState extends State<AddRemoveButton> {
      _qty = 0;
      cartInfo = Utils.getCartInfoByBusiness(store.state.cartInfos, widget.business);
      if (cartInfo != null) {
-        for (var i = 0; i < cartInfo.productList.length; i++) {
-          if (cartInfo.productList[i].product.id == widget.product.id) {
-            _qty = cartInfo.productList[i].quantity.round();
+        for (var i = 0; i < cartInfo.productList!.length; i++) {
+          if (cartInfo.productList![i].product!.id == widget.product.id) {
+            _qty = cartInfo.productList![i].quantity!.round();
            break;
          }
        }
      }
      if (widget.product.productAttributes != null &&
-          widget.product.productAttributes.length > 0 && widget.cartLineItemIndex == -1) {
+          widget.product.productAttributes!.length > 0 && widget.cartLineItemIndex == -1) {
        return new Row(
          key: startKey,
          crossAxisAlignment: CrossAxisAlignment.end,
@@ -312,7 +312,7 @@ class AddRemoveButtonState extends State<AddRemoveButton> {

  void _addToCart(BuildContext context) {
    if (widget.cartLineItemIndex != -1) {
-      if (cartInfo.productList[widget.cartLineItemIndex].quantity + 1.0 > widget.product.leftNum) {
+      if (cartInfo.productList![widget.cartLineItemIndex].quantity! + 1.0 > widget.product.leftNum) {
        Fluttertoast.showToast(
            msg: S.of(context).product_insufficient,
            toastLength: Toast.LENGTH_SHORT,
@@ -321,14 +321,14 @@ class AddRemoveButtonState extends State<AddRemoveButton> {
            textColor: Colors.white
        );
      } else {
-        cartInfo.productList[widget.cartLineItemIndex].quantity += 1.0;
-        Utils.addSubproductQty(cartInfo, cartInfo.productList[widget.cartLineItemIndex]);
+        cartInfo.productList![widget.cartLineItemIndex].quantity += 1.0;
+        Utils.addSubproductQty(cartInfo, cartInfo.productList![widget.cartLineItemIndex]);
        store.dispatch(UpdateCartInfo(
            Utils.addCartInfoToCartInfoList(store.state.cartInfos, cartInfo)));
        eventBus.fire(new OnCartInfoUpdated());
      }
    } else {
-      if (widget.product.productAttributes.length > 0) {
+      if (widget.product.productAttributes!.length > 0) {
        Navigator.push(
          context,
          MaterialPageRoute(builder: (context) =>
@@ -345,7 +345,7 @@ class AddRemoveButtonState extends State<AddRemoveButton> {

  void _removeFromCart(BuildContext context) {
    if (widget.cartLineItemIndex != -1) {
-      if (cartInfo.productList[widget.cartLineItemIndex].quantity <= 1) {
+      if (cartInfo.productList![widget.cartLineItemIndex].quantity! <= 1) {
        showDialog(
            context: context,
            builder: (BuildContext context) {
@@ -380,15 +380,15 @@ class AddRemoveButtonState extends State<AddRemoveButton> {
  }

  void _removeCartLineItem() {
-    if (cartInfo.productList[widget.cartLineItemIndex].quantity <= 1) {
-      String uuid = cartInfo.productList[widget.cartLineItemIndex].uuid;
-      cartInfo.productList.removeAt(widget.cartLineItemIndex);
+    if (cartInfo.productList![widget.cartLineItemIndex].quantity! <= 1) {
+      String uuid = cartInfo.productList![widget.cartLineItemIndex].uuid;
+      cartInfo.productList!.removeAt(widget.cartLineItemIndex);
      Utils.removeSubproduct(cartInfo, uuid);
    } else {
-      cartInfo.productList[widget.cartLineItemIndex].quantity -= 1;
-      Utils.addSubproductQty(cartInfo, cartInfo.productList[widget.cartLineItemIndex], remove: true);
+      cartInfo.productList![widget.cartLineItemIndex].quantity -= 1;
+      Utils.addSubproductQty(cartInfo, cartInfo.productList![widget.cartLineItemIndex], remove: true);
    }
-    if (cartInfo.productList.length <= 0) {
+    if (cartInfo.productList!.length <= 0) {
      store.dispatch(new UpdateCartInfo(Utils.removeCartInfoFromCartInfoList(store.state.cartInfos, cartInfo)));
    } else {
      store.dispatch(new UpdateCartInfo(Utils.addCartInfoToCartInfoList(store.state.cartInfos, cartInfo)));
--- a/lib/widgets/general/animation_point_manager.dart
+++ b/lib/widgets/general/animation_point_manager.dart
@@ -5,8 +5,8 @@ import 'popup_animation_widget.dart';

 class AnimationPointManager {
  List<AnimatedWidget> list = [];
-  static AnimationController controller1;
-  static AnimationController controller2;
+  static late AnimationController controller1;
+  static late AnimationController controller2;

  Future<void> addParabolicAniamtion({
    @required TickerProvider vsync,
@@ -55,9 +55,9 @@ class AnimationPointManager {
    @required GlobalKey stackKey,
    @required GlobalKey startKey,
    @required Widget child,
-    Duration duration,
+    Duration? duration,
    Offset popupOffset = Offset.zero,
-    AnimationStatusListener statusListener,
+    AnimationStatusListener? statusListener,
  }) async {
    controller2 = createController(vsync, duration);

--- a/lib/widgets/general/attribute/check_options.dart
+++ b/lib/widgets/general/attribute/check_options.dart
@@ -50,14 +50,14 @@ class CheckOptionsState extends OptionsBaseState<CheckOptions> {
              crossAxisAlignment: CrossAxisAlignment.start,
              children: <Widget>[
                new Text(
-                  S.of(context).check_option_select_token(product.productAttributes[this.index].name),
+                  S.of(context).check_option_select_token(product.productAttributes![this.index].name),
                  style: new TextStyle(
                    fontSize: 12.5,
                  ),
                  overflow: TextOverflow.ellipsis,
                ),
                new Text(
-                  product.productAttributes[this.index].required ? S.of(context).check_option_is_required : S.of(context).check_option_is_optional,
+                  product.productAttributes![this.index].required ? S.of(context).check_option_is_required : S.of(context).check_option_is_optional,
                  style: new TextStyle(
                    fontSize: 10.0,
                    color: new Color(0xFF999999)
@@ -95,20 +95,20 @@ class CheckOptionsState extends OptionsBaseState<CheckOptions> {
      'adjust_amount': adjustAmount
    };
    var cloneSelections = json.decode(json.encode(selections));
-    int idx = Utils.selectionsContains(cloneSelections, product.productAttributes[index].name, name);
+    int idx = Utils.selectionsContains(cloneSelections, product.productAttributes![index].name, name);
    if (idx != -1) {
-      (cloneSelections[product.productAttributes[index].name.toUpperCase()] as List).removeAt(idx);
-    } else if (cloneSelections.containsKey(product.productAttributes[index].name.toUpperCase())) {
-      (cloneSelections[product.productAttributes[index].name.toUpperCase()] as List).add(opt);
+      (cloneSelections[product.productAttributes![index].name!.toUpperCase()] as List).removeAt(idx);
+    } else if (cloneSelections.containsKey(product.productAttributes![index].name!.toUpperCase())) {
+      (cloneSelections[product.productAttributes![index].name!.toUpperCase()] as List).add(opt);
    } else {
-      cloneSelections[product.productAttributes[index].name.toUpperCase()] = [opt];
+      cloneSelections[product.productAttributes![index].name!.toUpperCase()] = [opt];
    }

-    if (idx != -1 && (cloneSelections[product.productAttributes[index].name.toUpperCase()] as List).length == 0) {
-      cloneSelections.remove(product.productAttributes[index].name.toUpperCase());
+    if (idx != -1 && (cloneSelections[product.productAttributes![index].name!.toUpperCase()] as List).length == 0) {
+      cloneSelections.remove(product.productAttributes![index].name!.toUpperCase());
    }

-    setOptionsStateDisabled(product.productAttributes[index].name, false);
+    setOptionsStateDisabled(product.productAttributes![index].name, false);

    setState(() {
      selections = cloneSelections;
@@ -121,20 +121,20 @@ class CheckOptionsState extends OptionsBaseState<CheckOptions> {
      children: <Widget>[],
    );

-    List<ProductOption> productOptions = product.productAttributes[index].productOptions;
+    List<ProductOption> productOptions = product.productAttributes![index].productOptions;

-    if (!optionsState.containsKey(product.productAttributes[index].name)) {
+    if (!optionsState.containsKey(product.productAttributes![index].name)) {
      List<Map<String, dynamic>> optionState = [];
      for (var i = 0; i < productOptions.length; i++) {
-        optionState.add({'name': product.productAttributes[index].productOptions[i].name, 'disabled': false, 'check': false});
+        optionState.add({'name': product.productAttributes![index].productOptions![i].name, 'disabled': false, 'check': false});
      }
-      optionsState[product.productAttributes[index].name] = optionState;
+      optionsState[product.productAttributes![index].name] = optionState;
    }

-    if (selections.containsKey(product.productAttributes[index].name.toUpperCase())) {
+    if (selections.containsKey(product.productAttributes![index].name!.toUpperCase())) {

      Map<String, dynamic> attrExtraJson = Utils.stringToJson(
-          product.productAttributes[index].extra);
+          product.productAttributes![index].extra);
      if (attrExtraJson != null) {
        var selectLimitIfFieldEqualsTo = Rule.getRule(
            attrExtraJson, Rule.RULE_SELECT_LIMIT_IF_FIELD_EQUALS_TO);
@@ -147,7 +147,7 @@ class CheckOptionsState extends OptionsBaseState<CheckOptions> {
                int limitQty = selectLimitIfFieldEqualsTo1[Rule
                    .RULE_KEY_FORCE_LIMITED];
                thisLimitQty = limitQty;
-                if ((selections[product.productAttributes[index].name
+                if ((selections[product.productAttributes![index].name
                    .toUpperCase()] as List).length >= limitQty) {
                  disableOptionIfNotSelected();
                }
@@ -155,7 +155,7 @@ class CheckOptionsState extends OptionsBaseState<CheckOptions> {
                if (selectLimitIfFieldEqualsTo1.containsKey(Utils.getSelectedAttributeValue(selections, selectLimitIfFieldEqualsTo1[Rule.RULE_KEY_FIELD_KEY])[0])) {
                  int limitQty = selectLimitIfFieldEqualsTo1[Utils.getSelectedAttributeValue(selections, selectLimitIfFieldEqualsTo1[Rule.RULE_KEY_FIELD_KEY])[0]];
                  thisLimitQty = limitQty;
-                  if ((selections[product.productAttributes[index].name
+                  if ((selections[product.productAttributes![index].name
                      .toUpperCase()] as List).length >= limitQty) {
                    disableOptionIfNotSelected();
                  }
@@ -168,7 +168,7 @@ class CheckOptionsState extends OptionsBaseState<CheckOptions> {
              int limitQty = selectLimitIfFieldEqualsTo[Rule
                  .RULE_KEY_FORCE_LIMITED];
              thisLimitQty = limitQty;
-              if ((selections[product.productAttributes[index].name
+              if ((selections[product.productAttributes![index].name
                  .toUpperCase()] as List).length >= limitQty) {
                disableOptionIfNotSelected();
              }
@@ -176,7 +176,7 @@ class CheckOptionsState extends OptionsBaseState<CheckOptions> {
              if (selectLimitIfFieldEqualsTo.containsKey(Utils.getSelectedAttributeValue(selections, selectLimitIfFieldEqualsTo[Rule.RULE_KEY_FIELD_KEY])[0])) {
                int limitQty = selectLimitIfFieldEqualsTo[Utils.getSelectedAttributeValue(selections, selectLimitIfFieldEqualsTo[Rule.RULE_KEY_FIELD_KEY])[0]];
                thisLimitQty = limitQty;
-                if ((selections[product.productAttributes[index].name
+                if ((selections[product.productAttributes![index].name
                    .toUpperCase()] as List).length >= limitQty) {
                  disableOptionIfNotSelected();
                }
@@ -195,12 +195,12 @@ class CheckOptionsState extends OptionsBaseState<CheckOptions> {
          Map<String, dynamic> multiItemRule = Rule.getRule(extraJson, Rule.RULE_ACTUAL_QTY_IS);
          if (exclusiveRule != null) {
            if (thisLimitQty > 0 && !_checkOptionIsCheck(productOptions[i].name)) {
-              optionsState[product.productAttributes[index].name][i]['disabled'] = true;
+              optionsState[product.productAttributes![index].name][i]['disabled'] = true;
            } else {
              if (_checkOptionIsCheck(productOptions[i].name)) {
                setOptionsStateDisabled(
-                    product.productAttributes[index].name, true);
-                optionsState[product.productAttributes[index]
+                    product.productAttributes![index].name, true);
+                optionsState[product.productAttributes![index]
                    .name][i]['disabled'] = false;
                break;
              }
@@ -208,12 +208,12 @@ class CheckOptionsState extends OptionsBaseState<CheckOptions> {
          }
          if (multiItemRule != null) {
            if (_checkOptionIsCheck(productOptions[i].name)) {
-              if (multiItemRule[Rule.RULE_ACTUAL_QTY_IS] > thisLimitQty - (selections[product.productAttributes[index].name.toUpperCase()] as List).length) {
+              if (multiItemRule[Rule.RULE_ACTUAL_QTY_IS] > thisLimitQty - (selections[product.productAttributes![index].name!.toUpperCase()] as List).length) {
                disableOptionIfNotSelected();
              }
            } else {
-              if (multiItemRule[Rule.RULE_ACTUAL_QTY_IS] > thisLimitQty - (selections[product.productAttributes[index].name.toUpperCase()] as List).length) {
-                optionsState[product.productAttributes[index]
+              if (multiItemRule[Rule.RULE_ACTUAL_QTY_IS] > thisLimitQty - (selections[product.productAttributes![index].name!.toUpperCase()] as List).length) {
+                optionsState[product.productAttributes![index]
                    .name][i]['disabled'] = true;
              }
            }
@@ -222,26 +222,26 @@ class CheckOptionsState extends OptionsBaseState<CheckOptions> {
      }
    }

-    List<Map<String, dynamic>> optionState = optionsState[product.productAttributes[index].name];
+    List<Map<String, dynamic>> optionState = optionsState[product.productAttributes![index].name];
    for (var i = 0; i < optionState.length; i++) {
      Widget optionWidget = _getOptionCheck(
-          product.productAttributes[index].productOptions[i], optionState[i]['disabled'], i);
+          product.productAttributes![index].productOptions![i], optionState[i]['disabled'], i);
      row.children.add(optionWidget);
    }
    return row;
  }

  void disableOptionIfNotSelected() {
-    setOptionsStateDisabled(product.productAttributes[index].name, true);
-    for (var i = 0; i < optionsState[product.productAttributes[index].name].length; i++) {
-      if (Utils.selectionsContains(selections, product.productAttributes[index].name, optionsState[product.productAttributes[index].name][i]['name']) != -1) {
-        optionsState[product.productAttributes[index].name][i]['disabled'] = false;
+    setOptionsStateDisabled(product.productAttributes![index].name, true);
+    for (var i = 0; i < optionsState[product.productAttributes![index].name].length; i++) {
+      if (Utils.selectionsContains(selections, product.productAttributes![index].name, optionsState[product.productAttributes![index].name][i]['name']) != -1) {
+        optionsState[product.productAttributes![index].name][i]['disabled'] = false;
      }
    }
  }

  bool _checkOptionIsCheck(String name) {
-    if (Utils.selectionsContains(selections, product.productAttributes[index].name, name) != -1) {
+    if (Utils.selectionsContains(selections, product.productAttributes![index].name, name) != -1) {
      return true;
    }
    return false;
@@ -343,7 +343,7 @@ class CheckOptionsState extends OptionsBaseState<CheckOptions> {
              overflow: TextOverflow.ellipsis,
            ),
            new Text(
-              (productOption.adjustAmount + extraAdjustAmount) > 0 ? '+${(productOption.adjustAmount + extraAdjustAmount).toStringAsFixed(2)}' : '',
+              (productOption.adjustAmount! + extraAdjustAmount) > 0 ? '+${(productOption.adjustAmount! + extraAdjustAmount).toStringAsFixed(2)}' : '',
              style: new TextStyle(
                fontSize: 11.0,
                color: check ? selectedTextColor : new Color(0xFFABABAB),
@@ -354,7 +354,7 @@ class CheckOptionsState extends OptionsBaseState<CheckOptions> {
        ),
      ),
      onTap: () => disabled ? null : _onOptionTappedCallback(
-          productOption.name, 0, productOption.adjustAmount + extraAdjustAmount, optIndex, productOption),
+          productOption.name, 0, productOption.adjustAmount! + extraAdjustAmount, optIndex, productOption),
    );
  }

--- a/lib/widgets/general/attribute/options_base.dart
+++ b/lib/widgets/general/attribute/options_base.dart
@@ -16,9 +16,9 @@ abstract class OptionsBase extends StatefulWidget {
 }

 abstract class OptionsBaseState<Base extends OptionsBase> extends State<Base> {
-  Product product;
-  Map<String, dynamic> selections;
-  int index;
+  late Product product;
+  late Map<String, dynamic> selections;
+  late int index;

  final Color disabledBackgroundColor = new Color(0xFFBCBCBC);

--- a/lib/widgets/general/attribute/qty_options.dart
+++ b/lib/widgets/general/attribute/qty_options.dart
@@ -41,14 +41,14 @@ class QtyOptionsState extends OptionsBaseState<QtyOptions> {
              crossAxisAlignment: CrossAxisAlignment.start,
              children: <Widget>[
                new Text(
-                  S.of(context).check_option_select_token(product.productAttributes[this.index].name),
+                  S.of(context).check_option_select_token(product.productAttributes![this.index].name),
                  style: new TextStyle(
                    fontSize: 12.5,
                  ),
                  overflow: TextOverflow.ellipsis,
                ),
                new Text(
-                  product.productAttributes[this.index].required ? S.of(context).check_option_is_required : S.of(context).check_option_is_optional,
+                  product.productAttributes![this.index].required ? S.of(context).check_option_is_required : S.of(context).check_option_is_optional,
                  style: new TextStyle(
                    fontSize: 10.0,
                    color: new Color(0xFF999999)
@@ -86,33 +86,33 @@ class QtyOptionsState extends OptionsBaseState<QtyOptions> {
      'adjust_amount': adjustAmount
    };
    var cloneSelections = json.decode(json.encode(selections));
-    int idx = Utils.selectionsContains(cloneSelections, product.productAttributes[index].name, name);
+    int idx = Utils.selectionsContains(cloneSelections, product.productAttributes![index].name, name);
    if (idx != -1) {
      if (quantity == 1) {
-        cloneSelections[product.productAttributes[index].name.toUpperCase()][idx]['quantity'] += 1;
-        optionsState[product.productAttributes[index].name][optIndex]['quantity'] = cloneSelections[product.productAttributes[index].name.toUpperCase()][idx]['quantity'];
+        cloneSelections[product.productAttributes![index].name!.toUpperCase()][idx]['quantity'] += 1;
+        optionsState[product.productAttributes![index].name][optIndex]['quantity'] = cloneSelections[product.productAttributes![index].name!.toUpperCase()][idx]['quantity'];
      } else {
-        if (cloneSelections[product.productAttributes[index].name.toUpperCase()][idx]['quantity'] - 1 > 0) {
-          cloneSelections[product.productAttributes[index].name.toUpperCase()][idx]['quantity'] -= 1;
-          optionsState[product.productAttributes[index].name][optIndex]['quantity'] = cloneSelections[product.productAttributes[index].name.toUpperCase()][idx]['quantity'];
+        if (cloneSelections[product.productAttributes![index].name!.toUpperCase()][idx]['quantity'] - 1 > 0) {
+          cloneSelections[product.productAttributes![index].name!.toUpperCase()][idx]['quantity'] -= 1;
+          optionsState[product.productAttributes![index].name][optIndex]['quantity'] = cloneSelections[product.productAttributes![index].name!.toUpperCase()][idx]['quantity'];
        } else {
-          (cloneSelections[product.productAttributes[index].name.toUpperCase()] as List).removeAt(idx);
-          optionsState[product.productAttributes[index].name][optIndex]['quantity'] = 0;
+          (cloneSelections[product.productAttributes![index].name!.toUpperCase()] as List).removeAt(idx);
+          optionsState[product.productAttributes![index].name][optIndex]['quantity'] = 0;
        }
      }
-    } else if (cloneSelections.containsKey(product.productAttributes[index].name.toUpperCase())) {
-      (cloneSelections[product.productAttributes[index].name.toUpperCase()] as List).add(opt);
-      optionsState[product.productAttributes[index].name][optIndex]['quantity'] = 1;
+    } else if (cloneSelections.containsKey(product.productAttributes![index].name!.toUpperCase())) {
+      (cloneSelections[product.productAttributes![index].name!.toUpperCase()] as List).add(opt);
+      optionsState[product.productAttributes![index].name][optIndex]['quantity'] = 1;
    } else {
-      cloneSelections[product.productAttributes[index].name.toUpperCase()] = [opt];
-      optionsState[product.productAttributes[index].name][optIndex]['quantity'] = 1;
+      cloneSelections[product.productAttributes![index].name!.toUpperCase()] = [opt];
+      optionsState[product.productAttributes![index].name][optIndex]['quantity'] = 1;
    }

-    if (idx != -1 && (cloneSelections[product.productAttributes[index].name.toUpperCase()] as List).length == 0) {
-      cloneSelections.remove(product.productAttributes[index].name.toUpperCase());
+    if (idx != -1 && (cloneSelections[product.productAttributes![index].name!.toUpperCase()] as List).length == 0) {
+      cloneSelections.remove(product.productAttributes![index].name!.toUpperCase());
    }

-    setOptionsStateDisabled(product.productAttributes[index].name, false);
+    setOptionsStateDisabled(product.productAttributes![index].name, false);

    setState(() {
      selections = cloneSelections;
@@ -125,24 +125,24 @@ class QtyOptionsState extends OptionsBaseState<QtyOptions> {
      children: <Widget>[],
    );

-    List<ProductOption> productOptions = product.productAttributes[index].productOptions;
+    List<ProductOption> productOptions = product.productAttributes![index].productOptions;

-    if (!optionsState.containsKey(product.productAttributes[index].name)) {
+    if (!optionsState.containsKey(product.productAttributes![index].name)) {
      List<Map<String, dynamic>> optionState = [];
      for (var i = 0; i < productOptions.length; i++) {
        int qty = 0;
-        int idx = Utils.selectionsContains(selections, product.productAttributes[index].name, productOptions[i].name);
+        int idx = Utils.selectionsContains(selections, product.productAttributes![index].name, productOptions[i].name);
        if (idx != -1) {
-          qty = selections[product.productAttributes[index].name.toUpperCase()][idx]['quantity'];
+          qty = selections[product.productAttributes![index].name!.toUpperCase()][idx]['quantity'];
        }
-        optionState.add({'name': product.productAttributes[index].productOptions[i].name, 'disabled': false, 'quantity': qty, 'check': false});
+        optionState.add({'name': product.productAttributes![index].productOptions![i].name, 'disabled': false, 'quantity': qty, 'check': false});
      }
-      optionsState[product.productAttributes[index].name] = optionState;
+      optionsState[product.productAttributes![index].name] = optionState;
    }

-    if (selections.containsKey(product.productAttributes[index].name.toUpperCase())) {
+    if (selections.containsKey(product.productAttributes![index].name!.toUpperCase())) {
      Map<String, dynamic> attrExtraJson = Utils.stringToJson(
-          product.productAttributes[index].extra);
+          product.productAttributes![index].extra);
      if (attrExtraJson != null) {
        var selectLimitIfFieldEqualsTo = Rule.getRule(
            attrExtraJson, Rule.RULE_SELECT_LIMIT_IF_FIELD_EQUALS_TO);
@@ -155,7 +155,7 @@ class QtyOptionsState extends OptionsBaseState<QtyOptions> {
                int limitQty = selectLimitIfFieldEqualsTo1[Rule
                    .RULE_KEY_FORCE_LIMITED];
                thisLimitQty = limitQty;
-                if ((selections[product.productAttributes[index].name
+                if ((selections[product.productAttributes![index].name
                    .toUpperCase()] as List).length >= limitQty) {
                  disableOptionIfNotSelected();
                }
@@ -163,7 +163,7 @@ class QtyOptionsState extends OptionsBaseState<QtyOptions> {
                if (selectLimitIfFieldEqualsTo1.containsKey(Utils.getSelectedAttributeValue(selections, selectLimitIfFieldEqualsTo1[Rule.RULE_KEY_FIELD_KEY])[0])) {
                  int limitQty = selectLimitIfFieldEqualsTo1[Utils.getSelectedAttributeValue(selections, selectLimitIfFieldEqualsTo1[Rule.RULE_KEY_FIELD_KEY])[0]];
                  thisLimitQty = limitQty;
-                  if ((selections[product.productAttributes[index].name
+                  if ((selections[product.productAttributes![index].name
                      .toUpperCase()] as List).length >= limitQty) {
                    disableOptionIfNotSelected();
                  }
@@ -176,7 +176,7 @@ class QtyOptionsState extends OptionsBaseState<QtyOptions> {
              int limitQty = selectLimitIfFieldEqualsTo[Rule
                  .RULE_KEY_FORCE_LIMITED];
              thisLimitQty = limitQty;
-              if ((selections[product.productAttributes[index].name
+              if ((selections[product.productAttributes![index].name
                  .toUpperCase()] as List).length >= limitQty) {
                disableOptionIfNotSelected();
              }
@@ -184,7 +184,7 @@ class QtyOptionsState extends OptionsBaseState<QtyOptions> {
              if (selectLimitIfFieldEqualsTo.containsKey(Utils.getSelectedAttributeValue(selections, selectLimitIfFieldEqualsTo[Rule.RULE_KEY_FIELD_KEY])[0])) {
                int limitQty = selectLimitIfFieldEqualsTo[Utils.getSelectedAttributeValue(selections, selectLimitIfFieldEqualsTo[Rule.RULE_KEY_FIELD_KEY])[0]];
                thisLimitQty = limitQty;
-                if ((selections[product.productAttributes[index].name
+                if ((selections[product.productAttributes![index].name
                    .toUpperCase()] as List).length >= limitQty) {
                  disableOptionIfNotSelected();
                }
@@ -203,12 +203,12 @@ class QtyOptionsState extends OptionsBaseState<QtyOptions> {
          Map<String, dynamic> multiItemRule = Rule.getRule(extraJson, Rule.RULE_ACTUAL_QTY_IS);
          if (exclusiveRule != null) {
            if (thisLimitQty > 0 && !_checkOptionIsCheck(productOptions[i].name)) {
-              optionsState[product.productAttributes[index].name][i]['disabled'] = true;
+              optionsState[product.productAttributes![index].name][i]['disabled'] = true;
            } else {
              if (_checkOptionIsCheck(productOptions[i].name)) {
                setOptionsStateDisabled(
-                    product.productAttributes[index].name, true);
-                optionsState[product.productAttributes[index]
+                    product.productAttributes![index].name, true);
+                optionsState[product.productAttributes![index]
                    .name][i]['disabled'] = false;
                break;
              }
@@ -216,12 +216,12 @@ class QtyOptionsState extends OptionsBaseState<QtyOptions> {
          }
          if (multiItemRule != null) {
            if (_checkOptionIsCheck(productOptions[i].name)) {
-              if (multiItemRule[Rule.RULE_ACTUAL_QTY_IS] > thisLimitQty - (selections[product.productAttributes[index].name.toUpperCase()] as List).length) {
+              if (multiItemRule[Rule.RULE_ACTUAL_QTY_IS] > thisLimitQty - (selections[product.productAttributes![index].name!.toUpperCase()] as List).length) {
                disableOptionIfNotSelected();
              }
            } else {
-              if (multiItemRule[Rule.RULE_ACTUAL_QTY_IS] > thisLimitQty - (selections[product.productAttributes[index].name.toUpperCase()] as List).length) {
-                optionsState[product.productAttributes[index]
+              if (multiItemRule[Rule.RULE_ACTUAL_QTY_IS] > thisLimitQty - (selections[product.productAttributes![index].name!.toUpperCase()] as List).length) {
+                optionsState[product.productAttributes![index]
                    .name][i]['disabled'] = true;
              }
            }
@@ -230,26 +230,26 @@ class QtyOptionsState extends OptionsBaseState<QtyOptions> {
      }
    }

-    List<Map<String, dynamic>> optionState = optionsState[product.productAttributes[index].name];
+    List<Map<String, dynamic>> optionState = optionsState[product.productAttributes![index].name];
    for (var i = 0; i < optionState.length; i++) {
      Widget optionWidget = _getOptionQty(
-          product.productAttributes[index].productOptions[i], optionState[i]['disabled'], optionState[i]['quantity'], i);
+          product.productAttributes![index].productOptions![i], optionState[i]['disabled'], optionState[i]['quantity'], i);
      row.children.add(optionWidget);
    }
    return row;
  }

  void disableOptionIfNotSelected() {
-    setOptionsStateDisabled(product.productAttributes[index].name, true);
-    for (var i = 0; i < optionsState[product.productAttributes[index].name].length; i++) {
-      if (Utils.selectionsContains(selections, product.productAttributes[index].name, optionsState[product.productAttributes[index].name][i]['name']) != -1) {
-        optionsState[product.productAttributes[index].name][i]['disabled'] = false;
+    setOptionsStateDisabled(product.productAttributes![index].name, true);
+    for (var i = 0; i < optionsState[product.productAttributes![index].name].length; i++) {
+      if (Utils.selectionsContains(selections, product.productAttributes![index].name, optionsState[product.productAttributes![index].name][i]['name']) != -1) {
+        optionsState[product.productAttributes![index].name][i]['disabled'] = false;
      }
    }
  }

  bool _checkOptionIsCheck(String name) {
-    if (Utils.selectionsContains(selections, product.productAttributes[index].name, name) != -1) {
+    if (Utils.selectionsContains(selections, product.productAttributes![index].name, name) != -1) {
      return true;
    }
    return false;
@@ -361,7 +361,7 @@ class QtyOptionsState extends OptionsBaseState<QtyOptions> {
                    overflow: TextOverflow.ellipsis,
                  ),
                  new Text(
-                    (productOption.adjustAmount + extraAdjustAmount) > 0 ? '+${(productOption.adjustAmount + extraAdjustAmount).toStringAsFixed(2)}' : '',
+                    (productOption.adjustAmount! + extraAdjustAmount) > 0 ? '+${(productOption.adjustAmount! + extraAdjustAmount).toStringAsFixed(2)}' : '',
                    style: new TextStyle(
                      fontSize: 11.0,
                      color: check ? selectedTextColor : new Color(0xFFABABAB),
@@ -372,7 +372,7 @@ class QtyOptionsState extends OptionsBaseState<QtyOptions> {
              ),
            ),
            onTap: () => disabled ? null : _onOptionTappedCallback(
-                productOption.name, 1, productOption.adjustAmount + extraAdjustAmount, optIndex, productOption),
+                productOption.name, 1, productOption.adjustAmount! + extraAdjustAmount, optIndex, productOption),
          ),
          new Container(
            width: 100.0,
@@ -406,7 +406,7 @@ class QtyOptionsState extends OptionsBaseState<QtyOptions> {
                      ),
                    ),
                    onTap: () => disabled ? null : _onOptionTappedCallback(
-                        productOption.name, 1, productOption.adjustAmount + extraAdjustAmount, optIndex, productOption),
+                        productOption.name, 1, productOption.adjustAmount! + extraAdjustAmount, optIndex, productOption),
                  ),
                ),
                new Expanded(
@@ -420,7 +420,7 @@ class QtyOptionsState extends OptionsBaseState<QtyOptions> {
                      ),
                    ),
                    onTap: () => (disabled || quantity == 0) ? null : _onOptionTappedCallback(
-                        productOption.name, -1, productOption.adjustAmount + extraAdjustAmount, optIndex, productOption),
+                        productOption.name, -1, productOption.adjustAmount! + extraAdjustAmount, optIndex, productOption),
                  ),
                ),
              ],
--- a/lib/widgets/general/attribute/radio_options.dart
+++ b/lib/widgets/general/attribute/radio_options.dart
@@ -40,14 +40,14 @@ class RadioOptionsState extends OptionsBaseState<RadioOptions> {
              crossAxisAlignment: CrossAxisAlignment.start,
              children: <Widget>[
                new Text(
-                  S.of(context).radio_option_select_token(product.productAttributes[this.index].name),
+                  S.of(context).radio_option_select_token(product.productAttributes![this.index].name),
                  style: new TextStyle(
                    fontSize: 12.5,
                  ),
                  overflow: TextOverflow.ellipsis,
                ),
                new Text(
-                  product.productAttributes[this.index].required ? S.of(context).radio_option_is_required : S.of(context).radio_option_is_optional,
+                  product.productAttributes![this.index].required ? S.of(context).radio_option_is_required : S.of(context).radio_option_is_optional,
                  style: new TextStyle(
                    fontSize: 10.0,
                    color: new Color(0xFF999999)
@@ -85,14 +85,14 @@ class RadioOptionsState extends OptionsBaseState<RadioOptions> {
      'adjust_amount': adjustAmount
    };
    var cloneSelections = json.decode(json.encode(selections));
-    if (product.productAttributes[index].required) {
-      cloneSelections[product.productAttributes[index].name.toUpperCase()] = [opt];
+    if (product.productAttributes![index].required) {
+      cloneSelections[product.productAttributes![index].name!.toUpperCase()] = [opt];
    } else {
-      if (cloneSelections.containsKey(product.productAttributes[index].name.toUpperCase())
-          && Utils.equalsIgnoreCase(cloneSelections[product.productAttributes[index].name.toUpperCase()][0]['name'], name)) {
-        cloneSelections.remove(product.productAttributes[index].name.toUpperCase());
+      if (cloneSelections.containsKey(product.productAttributes![index].name!.toUpperCase())
+          && Utils.equalsIgnoreCase(cloneSelections[product.productAttributes![index].name!.toUpperCase()][0]['name'], name)) {
+        cloneSelections.remove(product.productAttributes![index].name!.toUpperCase());
      } else {
-        cloneSelections[product.productAttributes[index].name.toUpperCase()] = [opt];
+        cloneSelections[product.productAttributes![index].name!.toUpperCase()] = [opt];
      }
    }

@@ -102,7 +102,7 @@ class RadioOptionsState extends OptionsBaseState<RadioOptions> {
          extraJson, Rule.RULE_EXCLUSIVE_SELECTION);
      if (exclusiveRule != null) {
        if (_checkOptionIsCheck(productOption.name)) {
-          setOptionsStateDisabled(product.productAttributes[index].name, false);
+          setOptionsStateDisabled(product.productAttributes![index].name, false);
        }
      }
    }
@@ -118,14 +118,14 @@ class RadioOptionsState extends OptionsBaseState<RadioOptions> {
      children: <Widget>[],
    );

-    List<ProductOption> productOptions = product.productAttributes[index].productOptions;
+    List<ProductOption> productOptions = product.productAttributes![index].productOptions;

-    if (!optionsState.containsKey(product.productAttributes[index].name)) {
+    if (!optionsState.containsKey(product.productAttributes![index].name)) {
      List<Map<String, dynamic>> optionState = [];
      for (var i = 0; i < productOptions.length; i++) {
-        optionState.add({'name': product.productAttributes[index].productOptions[i].name, 'disabled': false, 'check': false});
+        optionState.add({'name': product.productAttributes![index].productOptions![i].name, 'disabled': false, 'check': false});
      }
-      optionsState[product.productAttributes[index].name] = optionState;
+      optionsState[product.productAttributes![index].name] = optionState;
    }

    for (var i = 0; i < productOptions.length; i++) {
@@ -135,25 +135,25 @@ class RadioOptionsState extends OptionsBaseState<RadioOptions> {
            extraJson, Rule.RULE_EXCLUSIVE_SELECTION);
        if (exclusiveRule != null) {
          if (_checkOptionIsCheck(productOptions[i].name)) {
-            setOptionsStateDisabled(product.productAttributes[index].name, true);
-            optionsState[product.productAttributes[index].name][i]['disabled'] = false;
+            setOptionsStateDisabled(product.productAttributes![index].name, true);
+            optionsState[product.productAttributes![index].name][i]['disabled'] = false;
            break;
          }
        }
      }
    }

-    List<Map<String, dynamic>> optionState = optionsState[product.productAttributes[index].name];
+    List<Map<String, dynamic>> optionState = optionsState[product.productAttributes![index].name];
    for (var i = 0; i < optionState.length; i++) {
      Widget optionWidget = _getOptionRadio(
-          product.productAttributes[index].productOptions[i], optionState[i]['disabled'], i);
+          product.productAttributes![index].productOptions![i], optionState[i]['disabled'], i);
      row.children.add(optionWidget);
    }
    return row;
  }

  bool _checkOptionIsCheck(String name) {
-    if (Utils.selectionsContains(selections, product.productAttributes[index].name, name) != -1) {
+    if (Utils.selectionsContains(selections, product.productAttributes![index].name, name) != -1) {
      return true;
    }
    return false;
@@ -255,7 +255,7 @@ class RadioOptionsState extends OptionsBaseState<RadioOptions> {
              overflow: TextOverflow.ellipsis,
            ),
            new Text(
-              (productOption.adjustAmount + extraAdjustAmount) > 0 ? '+${(productOption.adjustAmount + extraAdjustAmount).toStringAsFixed(2)}' : '',
+              (productOption.adjustAmount! + extraAdjustAmount) > 0 ? '+${(productOption.adjustAmount! + extraAdjustAmount).toStringAsFixed(2)}' : '',
              style: new TextStyle(
                fontSize: 11.0,
                color: check ? selectedTextColor : new Color(0xFFABABAB),
@@ -266,7 +266,7 @@ class RadioOptionsState extends OptionsBaseState<RadioOptions> {
        ),
      ),
      onTap: () => disabled ? null : _onOptionTappedCallback(
-          productOption.name, 0, productOption.adjustAmount + extraAdjustAmount, optIndex, productOption),
+          productOption.name, 0, productOption.adjustAmount! + extraAdjustAmount, optIndex, productOption),
    );
  }

--- a/lib/widgets/general/carousel.dart
+++ b/lib/widgets/general/carousel.dart
@@ -6,8 +6,8 @@ import 'style.dart';
 class Carousel extends StatefulWidget {
  Carousel({
    double height = 200.0,
-    List<Widget> pages,
-    bool autoPlay,
+    List<Widget>? pages,
+    bool? autoPlay,
    Duration duration = const Duration(seconds: 2),
    Duration animationDuration = const Duration(milliseconds: 1000),
  })
@@ -30,7 +30,7 @@ class Carousel extends StatefulWidget {
 class CarouselState extends State<Carousel> {
  final _pageController = new PageController();

-  Timer _timer;
+  late Timer _timer;
  int _currentPage = 0;
  bool reverse = false;
  GlobalKey<IndicatorState> _indicatorStateKey = new GlobalKey();
@@ -80,7 +80,7 @@ class CarouselState extends State<Carousel> {
            children: widget.pages,
            onPageChanged: (index) {
              _currentPage = index;
-              _indicatorStateKey.currentState.changeIndex(index);
+              _indicatorStateKey.currentState!.changeIndex(index);
            },
          ),
        ),
@@ -102,7 +102,7 @@ class CarouselState extends State<Carousel> {
 }

 class Indicator extends StatefulWidget {
-  Indicator({Key? key, int count})
+  Indicator({Key? key, int? count})
      : count = count,
        super(key: key);

--- a/lib/widgets/general/e_transfer_pay.dart
+++ b/lib/widgets/general/e_transfer_pay.dart
@@ -65,7 +65,7 @@ class ETransferPay extends StatelessWidget {
                            fontSize: 15, color: Colors.black54),
                      ),
                      Text(
-                        '\$${order.totalPrice.toStringAsFixed(2)}',
+                        '\$${order.totalPrice!.toStringAsFixed(2)}',
                        style: const TextStyle(
                          fontSize: 28,
                          fontWeight: FontWeight.bold,
--- a/lib/widgets/general/parabolic_animation_widget.dart
+++ b/lib/widgets/general/parabolic_animation_widget.dart
@@ -11,7 +11,7 @@ class ParabolicAnimationWidget extends AnimatedWidget {
  final Offset startAdjustOffset;
  final Offset endAdjustOffset;

-  ParabolicAnimationWidget({
+  late ParabolicAnimationWidget({
    @required Animation<double> animation,
    @required this.stackKey,
    @required this.startKey,
@@ -66,17 +66,17 @@ class ParabolicAnimationWidget extends AnimatedWidget {

  void _calPoints() {
    if (_startOffset == null) {
-      RenderBox stackBox = stackKey.currentContext.findRenderObject();
+      RenderBox stackBox = stackKey.currentContext!.findRenderObject();
      Offset stackBoxOffset = stackBox.globalToLocal(Offset.zero);

      EdgeInsets startMargin = _margin(startKey);
-      RenderBox startBox = startKey.currentContext.findRenderObject();
+      RenderBox startBox = startKey.currentContext!.findRenderObject();
      _startOffset = startBox.localToGlobal(Offset(
          startMargin.left + startAdjustOffset.dx,
          stackBoxOffset.dy + startMargin.top + startAdjustOffset.dy));

      EdgeInsets endMargin = _margin(endKey);
-      RenderBox endBox = endKey.currentContext.findRenderObject();
+      RenderBox endBox = endKey.currentContext!.findRenderObject();
      _endOffset = endBox.localToGlobal(Offset(
          endMargin.left + endAdjustOffset.dx,
          stackBoxOffset.dy + endMargin.top + endAdjustOffset.dy));
@@ -84,7 +84,7 @@ class ParabolicAnimationWidget extends AnimatedWidget {
  }

  EdgeInsets _margin(GlobalKey key) {
-    final Widget widget = key.currentContext.widget;
+    final Widget widget = key.currentContext!.widget;
    EdgeInsets margin = (widget is Container) ? widget.margin : EdgeInsets.zero;
    return margin ?? EdgeInsets.zero;
  }
--- a/lib/widgets/general/payment_verification_code_dialog.dart
+++ b/lib/widgets/general/payment_verification_code_dialog.dart
@@ -33,8 +33,8 @@ class PaymentVerificationCodeDialogState extends State<PaymentVerificationCodeDi
  String getCodeText = '';
  String paymentCodeEncrypt = '';

-  String verifyMethod;
-  String verifyName;
+  late String verifyMethod;
+  late String verifyName;

  final TextEditingController _pinPutController = TextEditingController();
  final FocusNode _pinPutFocusNode = FocusNode();
--- a/lib/widgets/general/popup_animation_widget.dart
+++ b/lib/widgets/general/popup_animation_widget.dart
@@ -9,7 +9,7 @@ class PopupAnimationWidget extends AnimatedWidget {
  final Offset popupOffset;
  final Animation<double> animation;

-  PopupAnimationWidget({
+  late PopupAnimationWidget({
    @required this.animation,
    @required this.stackKey,
    @required this.startKey,
@@ -49,11 +49,11 @@ class PopupAnimationWidget extends AnimatedWidget {

  void _calAnimation() {
    if (_startOffset == null) {
-      final RenderBox stackBox = stackKey.currentContext.findRenderObject();
+      final RenderBox stackBox = stackKey.currentContext!.findRenderObject();
      final Offset stackBoxOffset = stackBox.globalToLocal(Offset.zero);

      final EdgeInsets startMargin = _margin(startKey);
-      final RenderBox startBox = startKey.currentContext.findRenderObject();
+      final RenderBox startBox = startKey.currentContext!.findRenderObject();

      _startOffset = startBox.localToGlobal(Offset(
          startMargin.left + popupOffset.dx,
@@ -62,7 +62,7 @@ class PopupAnimationWidget extends AnimatedWidget {
  }

  EdgeInsets _margin(GlobalKey key) {
-    final Widget widget = key.currentContext.widget;
+    final Widget widget = key.currentContext!.widget;
    final EdgeInsets margin =
    (widget is Container) ? widget.margin : EdgeInsets.zero;
    return margin ?? EdgeInsets.zero;
--- a/lib/widgets/general/sliding_up_panel.dart
+++ b/lib/widgets/general/sliding_up_panel.dart
@@ -211,9 +211,9 @@ class SlidingUpPanel extends StatefulWidget {

 class _SlidingUpPanelState extends State<SlidingUpPanel> with SingleTickerProviderStateMixin{

-  AnimationController _ac;
+  late AnimationController _ac;

-  ScrollController _sc;
+  late ScrollController _sc;
  bool _scrollingEnabled = false;
  VelocityTracker _vt = VelocityTracker.withKind(PointerDeviceKind.touch);

@@ -390,7 +390,7 @@ class _SlidingUpPanelState extends State<SlidingUpPanel> with SingleTickerProvid
  // and a listener if panelBuilder is used.
  // this is because the listener is designed only for use with linking the scrolling of
  // panels and using it for panels that don't want to linked scrolling yields odd results
-  Widget _gestureHandler({Widget child}){
+  Widget _gestureHandler({Widget? child}){
    if (!widget.isDraggable) return child;

    if (widget.panel != null){
@@ -552,14 +552,14 @@ class _SlidingUpPanelState extends State<SlidingUpPanel> with SingleTickerProvid

  //animate the panel position to value - must
  //be between 0.0 and 1.0
-  Future<void> _animatePanelToPosition(double value, {Duration duration, Curve curve = Curves.linear}){
+  Future<void> _animatePanelToPosition(double value, {Duration? duration, Curve curve = Curves.linear}){
    assert(0.0 <= value && value <= 1.0);
    return _ac.animateTo(value, duration: duration, curve: curve);
  }

  //animate the panel position to the snap point
  //REQUIRES that widget.snapPoint != null
-  Future<void> _animatePanelToSnapPoint({Duration duration, Curve curve = Curves.linear}){
+  Future<void> _animatePanelToSnapPoint({Duration? duration, Curve curve = Curves.linear}){
    assert(widget.snapPoint != null);
    return _ac.animateTo(widget.snapPoint, duration: duration, curve: curve);
  }
@@ -602,7 +602,7 @@ class _SlidingUpPanelState extends State<SlidingUpPanel> with SingleTickerProvid


 class PanelController{
-  _SlidingUpPanelState _panelState;
+  late _SlidingUpPanelState _panelState;

  void _addState(_SlidingUpPanelState panelState){
    this._panelState = panelState;
@@ -644,7 +644,7 @@ class PanelController{
  /// where 0.0 is fully collapsed and 1.0 is completely open.
  /// (optional) duration specifies the time for the animation to complete
  /// (optional) curve specifies the easing behavior of the animation.
-  Future<void> animatePanelToPosition(double value, {Duration duration, Curve curve = Curves.linear}){
+  Future<void> animatePanelToPosition(double value, {Duration? duration, Curve curve = Curves.linear}){
    assert(isAttached, "PanelController must be attached to a SlidingUpPanel");
    assert(0.0 <= value && value <= 1.0);
    return _panelState._animatePanelToPosition(value, duration: duration, curve: curve);
@@ -654,7 +654,7 @@ class PanelController{
  /// Requires that the SlidingUpPanel snapPoint property is not null
  /// (optional) duration specifies the time for the animation to complete
  /// (optional) curve specifies the easing behavior of the animation.
-  Future<void> animatePanelToSnapPoint({Duration duration, Curve curve = Curves.linear}){
+  Future<void> animatePanelToSnapPoint({Duration? duration, Curve curve = Curves.linear}){
    assert(isAttached, "PanelController must be attached to a SlidingUpPanel");
    assert(_panelState.widget.snapPoint != null, "SlidingUpPanel snapPoint property must not be null");
    return _panelState._animatePanelToSnapPoint(duration: duration, curve: curve);