ERROR Attempt to invoke virtual method 'java.lang.String java.lang.Object.toString()' on a null object reference

[qq329401134]

when i pickImage in gallerySource，example throw a error。 the details ：
E/flutter ( 6175): [ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: PlatformException(error, Attempt to invoke virtual method 'java.lang.String java.lang.Object.toString()' on a null object reference, null)
E/flutter ( 6175): #0 JSONMethodCodec.decodeEnvelope (package:flutter/src/services/message_codecs.dart:149:7)
E/flutter ( 6175): #1 MethodChannel.invokeMethod (package:flutter/src/services/platform_channel.dart:321:33)
E/flutter ( 6175):
E/flutter ( 6175): #2 OptionalMethodChannel.invokeMethod (package:flutter/src/services/platform_channel.dart:429:36)
E/flutter ( 6175): #3 TextInput._setEditingState (package:flutter/src/services/text_input.dart:1003:14)
E/flutter ( 6175): #4 TextInputConnection.setEditingState (package:flutter/src/services/text_input.dart:704:25)
E/flutter ( 6175): #5 InputConnectionController.updateRemoteValue (package:zefyr/src/widgets/input.dart:86:26)
E/flutter ( 6175): #6 _ZefyrEditableTextState._handleLocalValueChange (package:zefyr/src/widgets/editable_text.dart:298:12)
E/flutter ( 6175): #7 ChangeNotifier.notifyListeners (package:flutter/src/foundation/change_notifier.dart:206:21)
E/flutter ( 6175): #8 ZefyrController.formatText (package:zefyr/src/widgets/controller.dart:186:5)
E/flutter ( 6175): #9 ZefyrController.formatSelection (package:zefyr/src/widgets/controller.dart:193:5)
E/flutter ( 6175): #10 ZefyrScope.formatSelection (package:zefyr/src/widgets/scope.dart:181:17)
E/flutter ( 6175): #11 _ImageButtonState._pickFromGallery (package:zefyr/src/widgets/buttons.dart:293:14)
E/flutter ( 6175): #12 _asyncThenWrapperHelper. (dart:async-patch/async_patch.dart:73:64)
E/flutter ( 6175): #13 _rootRunUnary (dart:async/zone.dart:1134:38)
E/flutter ( 6175): #14 _CustomZone.runUnary (dart:async/zone.dart:1031:19)
E/flutter ( 6175): #15 _FutureListener.handleValue (dart:async/future_impl.dart:139:18)
E/flutter ( 6175): #16 Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:680:45)
E/flutter ( 6175): #17 Future._propagateToListeners (dart:async/future_impl.dart:709:32)
E/flutter ( 6175): #18 Future._completeWithValue (dart:async/future_impl.dart:524:5)
E/flutter ( 6175): #19 _AsyncAwaitCompleter.complete (dart:async-patch/async_patch.dart:32:15)
E/flutter ( 6175): #20 _completeOnAsyncReturn (dart:async-patch/async_patch.dart:290:13)
E/flutter ( 6175): #21 CustomImageDelegate.pickImage (package:laozhongjiadao001/zefyr/src/images.dart)
E/flutter ( 6175): #22 _asyncThenWrapperHelper. (dart:async-patch/async_patch.dart:73:64)
E/flutter ( 6175): #23 _rootRunUnary (dart:async/zone.dart:1134:38)
E/flutter ( 6175): #24 _CustomZone.runUnary (dart:async/zone.dart:1031:19)
E/flutter ( 6175): #25 _FutureListener.handleValue (dart:async/future_impl.dart:139:18)
E/flutter ( 6175): #26 Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:680:45)
E/flutter ( 6175): #27 Future._propagateToListeners (dart:async/future_impl.dart:709:32)
E/flutter ( 6175): #28 Future._completeWithValue (dart:async/future_impl.dart:524:5)
E/flutter ( 6175): #29 _AsyncAwaitCompleter.complete (dart:async-patch/async_patch.dart:32:15)
E/flutter ( 6175): #30 _completeOnAsyncReturn (dart:async-patch/async_patch.dart:290:13)
E/flutter ( 6175): #31 ImagePicker.pickImage (package:image_picker/image_picker.dart)
E/flutter ( 6175): #32 _asyncThenWrapperHelper. (dart:async-patch/async_patch.dart:73:64)
E/flutter ( 6175): #33 _rootRunUnary (dart:async/zone.dart:1134:38)
E/flutter ( 6175): #34 _CustomZone.runUnary (dart:async/zone.dart:1031:19)
E/flutter ( 6175): #35 _FutureListener.handleValue (dart:async/future_impl.dart:139:18)
E/flutter ( 6175): #36 Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:680:45)
E/flutter ( 6175): #37 Future._propagateToListeners (dart:async/future_impl.dart:709:32)
E/flutter ( 6175): #38 Future._completeWithValue (dart:async/future_impl.dart:524:5)
E/flutter ( 6175): #39 _AsyncAwaitCompleter.complete (dart:async-patch/async_patch.dart:32:15)
E/flutter ( 6175): #40 _completeOnAsyncReturn (dart:async-patch/async_patch.dart:290:13)
E/flutter ( 6175): #41 MethodChannel.invokeMethod (package:flutter/src/services/platform_channel.dart)
E/flutter ( 6175): #42 _asyncThenWrapperHelper. (dart:async-patch/async_patch.dart:73:64)
E/flutter ( 6175): #43 _rootRunUnary (dart:async/zone.dart:1134:38)
E/flutter ( 6175): #44 _CustomZone.runUnary (dart:async/zone.dart:1031:19)
E/flutter ( 6175): #45 _FutureListener.handleValue (dart:async/future_impl.dart:139:18)
E/flutter ( 6175): #46 Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:680:45)
E/flutter ( 6175): #47 Future._propagateToListeners (dart:async/futur
W/IInputConnectionWrapper( 6175): getTextBeforeCursor on inactive InputConnection
W/IInputConnectionWrapper( 6175): getTextBeforeCursor on inactive InputConnection
W/IInputConnectionWrapper( 6175): beginBatchEdit on inactive InputConnection
W/IInputConnectionWrapper( 6175): getTextAfterCursor on inactive InputConnection
W/IInputConnectionWrapper( 6175): endBatchEdit on inactive InputConnection
W/IInputConnectionWrapper( 6175): beginBatchEdit on inactive InputConnection
W/IInputConnectionWrapper( 6175): endBatchEdit on inactive InputConnection
W/IInputConnectionWrapper( 6175): beginBatchEdit on inactive InputConnection
W/IInputConnectionWrapper( 6175): endBatchEdit on inactive InputConnection
W/IInputConnectionWrapper( 6175): beginBatchEdit on inactive InputConnection
W/IInputConnectionWrapper( 6175): endBatchEdit on inactive InputConnection
how to fix it , help thank you