1. Run Gallery and select Text Fields
2. Set focus to an input widget
3. Use the back button to return to the Gallery home screen.
4. Press the Android power button. This throws the exception below.

The Keyboard Mojo service still holds a client stub for the input widget even after the widget is defunct.

0 ms • E/flutter : The null object does not have a method 'inheritFromWidgetOfExactType'.
0 ms • E/flutter :
0 ms • E/flutter : NoSuchMethodError: method not found: 'inheritFromWidgetOfExactType'
0 ms • E/flutter : Receiver: null
0 ms • E/flutter : Arguments: [Type: class 'FormScope']
0 ms • E/flutter : #0 Object._noSuchMethod (dart:core-patch/object_patch.dart:44)
0 ms • E/flutter : #1 Object.noSuchMethod (dart:core-patch/object_patch.dart:47)
0 ms • E/flutter : #2 FormScope.of (package:flutter/src/widgets/form.dart:102)
0 ms • E/flutter : #3 _FormFieldData.onChanged (package:flutter/src/material/input.dart:289)
0 ms • E/flutter : #4 RawInputLineState._handleTextUpdated (package:flutter/src/widgets/editable.dart:333)
0 ms • E/flutter : #5 _KeyboardClientImpl.updateEditingState (package:flutter/src/widgets/editable.dart:76)
0 ms • E/flutter : #6 _KeyboardClientStubControl.handleMessage (package:sky_services/editing/editing.mojom.dart:1133)
0 ms • E/flutter : #7 StubMessageHandler.handleRead (package:mojo/src/stub.dart:73)
0 ms • E/flutter : #8 MojoEventHandler._handleEvent (package:mojo/src/event_handler.dart:192)
0 ms • E/flutter : #9 MojoEventHandler._tryHandleEvent (package:mojo/src/event_handler.dart:168)