Crash in DraggableScrollableController.animateTo #125709
Description
b/279930163
Customer reports a crash happening with this stack trace:
flutter: The following _TypeError was thrown while notifying listeners for AnimationController:
flutter: Null check operator used on a null value
flutter:
flutter: When the exception was thrown, this was the stack:
flutter: #0 DraggableScrollableController.animateTo.<anonymous closure> (package:flutter/src/widgets/draggable_scrollable_sheet.dart:135:26)
flutter: #1 AnimationLocalListenersMixin.notifyListeners (package:flutter/src/animation/listener_helpers.dart:161:19)
flutter: #2 AnimationController._tick (package:flutter/src/animation/animation_controller.dart:830:5)
flutter: #3 Ticker._tick (package:flutter/src/scheduler/ticker.dart:249:12)
flutter: #4 SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1289:15)
flutter: #5 SchedulerBinding.handleBeginFrame.<anonymous closure> (package:flutter/src/scheduler/binding.dart:1141:11)
flutter: #6 _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:625:13)
flutter: #7 SchedulerBinding.handleBeginFrame (package:flutter/src/scheduler/binding.dart:1139:17)
flutter: #8 SchedulerBinding._handleBeginFrame (package:flutter/src/scheduler/binding.dart:1056:5)
flutter: #9 _invoke1 (dart:ui/hooks.dart:158:13)
flutter: #10 PlatformDispatcher._beginFrame (dart:ui/platform_dispatcher.dart:337:5)
flutter: #11 _beginFrame (dart:ui/hooks.dart:101:31)
I have not been able to reproduce the issue.
In the customer app, the scroll controller is shared across two different DraggableScrollableSheets that are switched out as they expand and collapse.
There is a button at the top of the sheet that triggers the _controller.animateTo in order to collapse and expand it.
There is also a change in the sheets' extents happening in response to scroll notifications that are listening to the sheet.
Similar to #112020