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_my_support.dart

@@ -28,7 +28,7 @@ class MobileMySupport extends StatefulWidget {
 }
 
 class MobileMySupportState extends State<MobileMySupport> {
-  List<Ticket> tickets;
+  late List<Ticket> tickets;
 
   int _page = 1;
   int _pageCount = 1;
@@ -179,7 +179,7 @@ class MobileMySupportState extends State<MobileMySupport> {
                         children: <Widget>[
                           Container(
                             child: Text(
-                              ticket.issue.msg,
+                              ticket.issue!.msg,
                               style: TextStyle(
                                 fontSize: 19.0,
                               ),
@@ -208,7 +208,7 @@ class MobileMySupportState extends State<MobileMySupport> {
                                 ) :
                                 SizedBox.shrink(),
                                 Text(
-                                  S.of(context).followups_token(ticket.followUps.length),
+                                  S.of(context).followups_token(ticket.followUps!.length),
                                   style: TextStyle(
                                     fontSize: 15.0,
                                     color: Colors.black87,