not work in WillPopScope （onWillPop）

[unclehking]

WillPopScope(
//
onWillPop: () async{
Toast.show("test",context);
}
)

E/flutter ( 2193): [ERROR:flutter/lib/ui/ui_dart_state.cc(148)] Unhandled Exception: NoSuchMethodError: The method 'insert' was called on null.
E/flutter ( 2193): Receiver: null
E/flutter ( 2193): Tried calling: insert(Instance of 'OverlayEntry')
E/flutter ( 2193): #0 Object.noSuchMethod (dart:core-patch/object_patch.dart:50:5)
E/flutter ( 2193): #1 ToastView.createView (package:toast/toast.dart:67:18)
E/flutter ( 2193):
E/flutter ( 2193): #2 Toast.show (package:toast/toast.dart:19:15)
E/flutter ( 2193): #3 AppState.build. (package:mama_call/main.dart:145:25)
E/flutter ( 2193): #4 _AsyncAwaitCompleter.start (dart:async-patch/async_patch.dart:49:6)
E/flutter ( 2193): #5 AppState.build. (package:mama_call/main.dart:141:26)
E/flutter ( 2193): #6 ModalRoute.willPop (package:flutter/src/widgets/routes.dart:1083:26)
E/flutter ( 2193): #7 _AsyncAwaitCompleter.start (dart:async-patch/async_patch.dart:49:6)
E/flutter ( 2193): #8 ModalRoute.willPop (package:flutter/src/widgets/routes.dart:1079:38)
E/flutter ( 2193): #9 NavigatorState.maybePop (package:flutter/src/widgets/navigator.dart:2004:57)
E/flutter ( 2193): #10 _AsyncAwaitCompleter.start (dart:async-patch/async_patch.dart:49:6)
E/flutter ( 2193): #11 NavigatorState.maybePop (package:flutter/src/widgets/navigator.dart:2001:42)
E/flutter ( 2193): #12 _WidgetsAppState.didPopRoute (package:flutter/src/widgets/app.dart:808:28)
E/flutter ( 2193): #13 _AsyncAwaitCompleter.start (dart:async-patch/async_patch.dart:49:6)
E/flutter ( 2193): #14 _WidgetsAppState.didPopRoute (package:flutter/src/widgets/app.dart:803:27)
E/flutter ( 2193): #15 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding&WidgetsBinding.handlePopRoute (package:flutter/src/widgets/binding.dart:482:26)
E/flutter ( 2193): #16 _AsyncAwaitCompleter.start (dart:async-patch/async_patch.dart:49:6)
E/flutter ( 2193): #17 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding&WidgetsBinding.handlePopRoute (package:flutter/src/widgets/binding.dart:480:30)
E/flutter ( 2193): #18 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding&WidgetsBinding._handleNavigationInvocation (package:flutter/src/widgets/binding.dart:510:16)
E/flutter ( 2193): #19 MethodChannel._handleAsMethodCall (package:flutter/src/services/platform_channel.dart:397:55)
E/flutter ( 2193): #20 _AsyncAwaitCompleter.start (dart:async-patch/async_patch.dart:49:6)
E/flutter ( 2193): #21 MethodChannel._handleAsMethodCall (package:flutter/src/services/platform_channel.dart:394:39)
E/flutter ( 2193): #22 MethodChannel.setMethodCallHandler. (package:flutter/src/services/platform_channel.dart:365:54)
E/flutter ( 2193): #23 _DefaultBinaryMessenger.handlePlatformMessage (package:flutter/src/services/binary_messenger.dart:110:33)
E/flutter ( 2193): #24 _AsyncAwaitCompleter.start (dart:async-patch/async_patch.dart:49:6)
E/flutter ( 2193): #25 _DefaultBinaryMessenger.handlePlatformMessage (package:flutter/src/services/binary_messenger.dart:101:37)
E/flutter ( 2193): #26 _invoke3. (dart:ui/hooks.dart:280:15)
E/flutter ( 2193): #27 _rootRun (dart:async/zone.dart:1124:13)
E/flutter ( 2193): #28 _CustomZone.run (dart:async/zone.dart:1021:19)
E/flutter ( 2193): #29 _CustomZone.runGuarded (dart:async/zone.dart:923:7)
E/flutter ( 2193): #30 _invoke3 (dart:ui/hooks.dart:279:10)
E/flutter ( 2193): #31 _dispatchPlatformMessage (dart:ui/hooks.dart:141:5)

[appdev]

You can update to new verision.
toast: ^0.1.4

[crtl]

I had the same issue using WillPopScope as a direct child of MaterialApp in the same widget.
Using a Builder and its BuildContext works for me.

This doesnt work:

/* ... */
MaterialApp(
  home: WillPopScope(
    onWillPop: () => Toast.show("Test", context),
    child: Navigator(),
  )
);
/* ... */

This does:

/* ... */
MaterialApp(
  home: Builder(
    builder: (_context) {
       return WillPopScope(
         onWillPop: () => Toast.show("Test", _context),
         child: Navigator(),
       )
    }
  )
);
/* ... */