Crash on hot reload

[leidig54]

Describe the bug
Showcase View is causing hot reload to crash the app.

To Reproduce
Steps to reproduce the behavior:

1. Change a widget.
2. Hit reload.
3. App crashes with below exception.

iOS and android. Simulator and physical devices.

Reloaded 7 of 1406 libraries in 2,257ms.
[VERBOSE-2:shell.cc(210)] Dart Unhandled Exception: This widget has been unmounted, so the State no longer has a context (and should be considered defunct).
Consider canceling any active work during "dispose" or using the "mounted" getter to determine if the State is still active., stack trace: #0      State.context.<anonymous closure>
package:flutter/…/widgets/framework.dart:1090
#1      State.context
package:flutter/…/widgets/framework.dart:1096
#2      _OverlayBuilderState.addToOverlay
package:showcaseview/layout_overlays.dart:165
#3      _OverlayBuilderState.showOverlay
package:showcaseview/layout_overlays.dart:157
#4      _OverlayBuilderState.syncWidgetAndOverlay
package:showcaseview/layout_overlays.dart:183
#5      _OverlayBuilderState.reassemble.<anonymous closure>
package:showcaseview/layout_overlays.dart:137
#6      SchedulerBinding._invokeFrameCallback
package:flutter/…/scheduler/binding.dart:1117
#7      SchedulerBinding.handleDrawFrame (package:flutter<…>

I'm not sure what to make of this. Does anyone have a good way of implementing the "mounted" feature mentioned in the exception? I have implemented the ShowCaseWidget like so...

return Builder(
          builder: (context) => (maskCategoryList.isNotEmpty ||
                  favouriteMask != null)
              ? ShowCaseWidget(
                  builder: Builder(builder: (context) {
                    WidgetsBinding.instance.addPostFrameCallback((_) async {
                      if (context
                              .read<UserDataRepo>()
                              .showCaseMap['maskHome'] !=
                          true) {
                        context.read<UserDataRepo>().setShowCase('maskHome');
                        return Future.delayed(Duration(milliseconds: 500)).then(
                            (value) => ShowCaseWidget.of(context).startShowCase(
                                [favouriteText, maskCategoryTile]));
                      }
                    });

                    return Padding(

[leidig54]

...solved fairly easily by wrapping the WidgetsBinding callback in a if(mounted). I'll leave this here incase anyone else needs the prompt...

[sanket-simform]

Thanks , we'll update sample accordingly in next release.

[tomassasovsky]

I also have this problem:

E/flutter ( 3726): [ERROR:flutter/shell/common/shell.cc(103)] Dart Unhandled Exception: This widget has been unmounted, so the State no longer has a context (and should be considered defunct).
E/flutter ( 3726): Consider canceling any active work during "dispose" or using the "mounted" getter to determine if the State is still active., stack trace: #0      State.context.<anonymous closure>
E/flutter ( 3726): #1      State.context
E/flutter ( 3726): #2      _OverlayBuilderState.addToOverlay
E/flutter ( 3726): #3      _OverlayBuilderState.showOverlay
E/flutter ( 3726): #4      _OverlayBuilderState.syncWidgetAndOverlay
E/flutter ( 3726): #5      _OverlayBuilderState.reassemble.<anonymous closure>
E/flutter ( 3726): #6      SchedulerBinding._invokeFrameCallback
E/flutter ( 3726): #7      SchedulerBinding.handleDrawFrame
E/flutter ( 3726): #8      SchedulerBinding.scheduleWarmUpFrame.<anonymous closure>
E/flutter ( 3726): #9      Timer._createTimer.<anonymous closure> (dart:async-patch/timer_patch.dart:18:15)
E/flutter ( 3726): #10     _Timer._runTimers (dart:isolate-patch/timer_impl.dart:395:19)
E/flutter ( 3726): #11     _Timer._handleMessage (dart:isolate-patch/timer_impl.dart:426:5)
E/flutter ( 3726): #12     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:184:12)
E/flutter ( 3726):

I tried this:

if (mounted)
      WidgetsBinding.instance?.addPostFrameCallback((_) {
        ShowCaseWidget.of(context)?.startShowCase(app.showcaseSettings.keys);
      });

inside my build method but this keeps happening. I also tried placing it inside the initState function but this error also appears.