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

lib/widgets/mobile/mobile_attribute_selection.dart

@@ -33,18 +33,18 @@ class MobileAttributeSelection extends StatefulWidget {
 }
 
 class MobileAttributeSelectionState extends State<MobileAttributeSelection> {
-  Product product;
-  int index;
-  TextButton previousButton;
-  TextButton nextButton;
-  bool previousButtonEnable;
-  bool nextButtonEnable;
+  late Product product;
+  late int index;
+  late TextButton previousButton;
+  late TextButton nextButton;
+  late bool previousButtonEnable;
+  late bool nextButtonEnable;
 
-  String productDesc;
-  double productPrice;
+  late String productDesc;
+  late double productPrice;
 
-  String nextText;
-  String finishText;
+  late String nextText;
+  late String finishText;
 
   Map<String, dynamic> selections = new Map();
 
@@ -118,31 +118,31 @@ class MobileAttributeSelectionState extends State<MobileAttributeSelection> {
         extendDescription.add(key + ': ' + opt.join(', '));
       });
 
-      ProductAttribute pa = product.productAttributes[index];
+      ProductAttribute pa = product.productAttributes![index];
       if (pa.required && Utils.selectionsNotEmptyAt(selections, pa.name)) {
         setState(() {
           nextButtonEnable = true;
-          productDesc = product.description + ', ' + extendDescription.join('; ');
-          productPrice = product.price + extendPrice;
+          productDesc = product.description! + ', ' + extendDescription.join('; ');
+          productPrice = product.price! + extendPrice;
         });
       } else if (!pa.required){
         setState(() {
           nextButtonEnable = true;
-          productDesc = product.description + ', ' + extendDescription.join('; ');
-          productPrice = product.price + extendPrice;
+          productDesc = product.description! + ', ' + extendDescription.join('; ');
+          productPrice = product.price! + extendPrice;
         });
       } else {
         setState(() {
           nextButtonEnable = false;
-          productDesc = product.description + ', ' + extendDescription.join('; ');
-          productPrice = product.price + extendPrice;
+          productDesc = product.description! + ', ' + extendDescription.join('; ');
+          productPrice = product.price! + extendPrice;
         });
       }
     });
   }
 
   bool _checkCanGoNext() {
-    ProductAttribute pa = product.productAttributes[index];
+    ProductAttribute pa = product.productAttributes![index];
     if (pa.required && Utils.selectionsNotEmptyAt(selections, pa.name)) {
       return true;
     } else if (!pa.required){
@@ -167,7 +167,7 @@ class MobileAttributeSelectionState extends State<MobileAttributeSelection> {
     nextButton = TextButton(
       onPressed: nextButtonEnable ? _goNext : null,
       child: new Text(
-          product.productAttributes.length > index + 1 ? nextText : finishText
+          product.productAttributes!.length > index + 1 ? nextText : finishText
       ),
     );
 
@@ -239,7 +239,7 @@ class MobileAttributeSelectionState extends State<MobileAttributeSelection> {
   Widget _getOptionsView() {
     Widget optionsView;
 
-    ProductAttribute productAttribute = product.productAttributes[index];
+    ProductAttribute productAttribute = product.productAttributes![index];
     if (productAttribute.byQuantity) {
       optionsView = new QtyOptions(product: product, index: index, selections: selections);
     } else {
@@ -254,13 +254,13 @@ class MobileAttributeSelectionState extends State<MobileAttributeSelection> {
   }
 
   void _goNext() {
-    if (index + 1 < product.productAttributes.length) {
+    if (index + 1 < product.productAttributes!.length) {
       setState(() {
         index = index + 1;
         previousButtonEnable = index >= 1;
         nextButtonEnable = _checkCanGoNext();
       });
-    } else if (product.productAttributes.length == index + 1) {
+    } else if (product.productAttributes!.length == index + 1) {
       eventBus.fire(new OnProductWillAddToCart(product, selections, productPrice, productDesc, widget.business, buttonKey: widget.startKey));
       Navigator.pop(context);
     }