Repository: flutter
Issue: `LateError: LateInitializationError: Local 'built' has not been initialized.`
Labels: c: crash,framework,a: null-safety,P2,team-framework,triaged-framework

Hello,

I am using latest flutter and flutter doctor shows no issues.

I see (live app) many errors like this: `LateError: LateInitializationError: Local 'built' has not been initialized.`
I am not sure is SilverAppBar is related but I saw those errors mostly when SIlverAppBar is involved.
I do not know how to solve them and why they are happening. Have you any clew what causes them. Here is stacktrace:

<details> 
<summary>logs</summary> 
	
```console
LateError: LateInitializationError: Local 'built' has not been initialized.
  File "internal_patch.dart", line 208, in LateError._throwLocalNotInitialized
  File "observer_widget_mixin.dart", line 86, in ObserverElementMixin.build
  File "framework.dart", line 4495, in ComponentElement.performRebuild
  File "framework.dart", line 4189, in Element.rebuild
  File "framework.dart", line 4576, in StatelessElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 5981, in SingleChildRenderObjectElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 5981, in SingleChildRenderObjectElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 4520, in ComponentElement.performRebuild
  File "framework.dart", line 4189, in Element.rebuild
  File "framework.dart", line 4576, in StatelessElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 4520, in ComponentElement.performRebuild
  File "framework.dart", line 4189, in Element.rebuild
  File "framework.dart", line 4843, in ProxyElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 4520, in ComponentElement.performRebuild
  File "framework.dart", line 4667, in StatefulElement.performRebuild
  File "framework.dart", line 4189, in Element.rebuild
  File "framework.dart", line 4699, in StatefulElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 4520, in ComponentElement.performRebuild
  File "framework.dart", line 4189, in Element.rebuild
  File "framework.dart", line 4576, in StatelessElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "sliver.dart", line 1229, in SliverMultiBoxAdaptorElement.updateChild
  File "sliver.dart", line 1145, in SliverMultiBoxAdaptorElement.performRebuild.processElement
  File "iterable.dart", line 257, in Iterable.forEach
  File "sliver.dart", line 1187, in SliverMultiBoxAdaptorElement.performRebuild
  File "sliver.dart", line 1124, in SliverMultiBoxAdaptorElement.update
File "framework.dart", line 3293, in Element.updateChild
  File "sliver.dart", line 1229, in SliverMultiBoxAdaptorElement.updateChild
  File "sliver.dart", line 1145, in SliverMultiBoxAdaptorElement.performRebuild.processElement
  File "iterable.dart", line 257, in Iterable.forEach
  File "sliver.dart", line 1187, in SliverMultiBoxAdaptorElement.performRebuild
  File "sliver.dart", line 1124, in SliverMultiBoxAdaptorElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 4520, in ComponentElement.performRebuild
  File "framework.dart", line 4189, in Element.rebuild
  File "framework.dart", line 4843, in ProxyElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 5981, in SingleChildRenderObjectElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 5503, in RenderObjectElement.updateChildren
  File "framework.dart", line 6105, in MultiChildRenderObjectElement.update
  File "viewport.dart", line 228, in _ViewportElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 5981, in SingleChildRenderObjectElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 5981, in SingleChildRenderObjectElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 5981, in SingleChildRenderObjectElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 5981, in SingleChildRenderObjectElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 4520, in ComponentElement.performRebuild
  File "framework.dart", line 4667, in StatefulElement.performRebuild
  File "framework.dart", line 4189, in Element.rebuild
  File "framework.dart", line 4699, in StatefulElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 5981, in SingleChildRenderObjectElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 4520, in ComponentElement.performRebuild
  File "framework.dart", line 4189, in Element.rebuild
  File "framework.dart", line 4843, in ProxyElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 5981, in SingleChildRenderObjectElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 5981, in SingleChildRenderObjectElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 5981, in SingleChildRenderObjectElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 5981, in SingleChildRenderObjectElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 4520, in ComponentElement.performRebuild
  File "framework.dart", line 4189, in Element.rebuild
  File "framework.dart", line 4576, in StatelessElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 4520, in ComponentElement.performRebuild
  File "framework.dart", line 4667, in StatefulElement.performRebuild
  File "framework.dart", line 4189, in Element.rebuild
  File "framework.dart", line 4699, in StatefulElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 4520, in ComponentElement.performRebuild
  File "framework.dart", line 4667, in StatefulElement.performRebuild
  File "framework.dart", line 4189, in Element.rebuild
  File "framework.dart", line 4699, in StatefulElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 4520, in ComponentElement.performRebuild
  File "framework.dart", line 4189, in Element.rebuild
  File "framework.dart", line 4843, in ProxyElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 4520, in ComponentElement.performRebuild
  File "framework.dart", line 4189, in Element.rebuild
  File "framework.dart", line 4576, in StatelessElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 4520, in ComponentElement.performRebuild
  File "framework.dart", line 4667, in StatefulElement.performRebuild
  File "framework.dart", line 4189, in Element.rebuild
  File "framework.dart", line 4699, in StatefulElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 5981, in SingleChildRenderObjectElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 4520, in ComponentElement.performRebuild
  File "framework.dart", line 4189, in Element.rebuild
  File "framework.dart", line 4576, in StatelessElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 5981, in SingleChildRenderObjectElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 4520, in ComponentElement.performRebuild
  File "framework.dart", line 4189, in Element.rebuild
  File "framework.dart", line 4576, in StatelessElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 4520, in ComponentElement.performRebuild
  File "framework.dart", line 4189, in Element.rebuild
  File "framework.dart", line 4576, in StatelessElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 4520, in ComponentElement.performRebuild
  File "framework.dart", line 4189, in Element.rebuild
  File "framework.dart", line 4576, in StatelessElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 4520, in ComponentElement.performRebuild
  File "framework.dart", line 4189, in Element.rebuild
  File "framework.dart", line 4576, in StatelessElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 5503, in RenderObjectElement.updateChildren
  File "framework.dart", line 6105, in MultiChildRenderObjectElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 4520, in ComponentElement.performRebuild
  File "framework.dart", line 4667, in StatefulElement.performRebuild
  File "framework.dart", line 4189, in Element.rebuild
  File "framework.dart", line 4699, in StatefulElement.update
  File "framework.dart", line 3293, in Element.updateChild
  File "framework.dart", line 4520, in ComponentElement.performRebuild
  File "framework.dart", line 4189, in Element.rebuild
  File "framework.dart", line 2694, in BuildOwner.buildScope
  File "binding.dart", line 873, in WidgetsBinding.drawFrame
  File "binding.dart", line 319, in RendererBinding._handlePersistentFrameCallback
  File "binding.dart", line 1144, in SchedulerBinding._invokeFrameCallback
  File "binding.dart", line 1082, in SchedulerBinding.handleDrawFrame
  File "binding.dart", line 998, in SchedulerBinding._handleDrawFrame
  File "zone.dart", line 1354, in _rootRun
  File "zone.dart", line 1258, in _CustomZone.run
  File "zone.dart", line 1162, in _CustomZone.runGuarded
  File "hooks.dart", line 161, in _invoke
  File "platform_dispatcher.dart", line 253, in PlatformDispatcher._drawFrame
  File "hooks.dart", line 120, in _drawFrame
```

</details>