AssertionError in Flutter rendering pipeline during navigation #502
Description
In checked mode, navigating around a Flutter app (via app-code-based navigation or the back button) yields the following assertion error:
android: I/flutter : -- EXCEPTION IN SCHEDULER CALLBACK --
android: I/flutter : 'packages/flutter/src/rendering/object.dart': Failed assertion: line 374: '_renderObject != null' is not true.
android: I/flutter : Stack trace:
android: I/flutter : #0 _AssertionError._throwNew (dart:core-patch/errors_patch.dart:27)
android: I/flutter : #1 Painter.detach (packages/flutter/src/rendering/object.dart:374)
android: I/flutter : #2 ScrollbarPainter.detach (packages/flutter/src/material/scrollbar_painter.dart:78)
android: I/flutter : #3 RenderBlockViewport.overlayPainter= (packages/flutter/src/rendering/block.dart:311)
android: I/flutter : #4 _HomogeneousViewportElement.unmount (packages/flutter/src/widgets/homogeneous_viewport.dart:84)
android: I/flutter : #5 _InactiveElements._unmount (packages/flutter/src/widgets/framework.dart:476)
android: I/flutter : #6 _InactiveElements._unmount.<anonymous closure> (packages/flutter/src/widgets/framework.dart:480)
android: I/flutter : #7 OneChildRenderObjectElement.visitChildren (packages/flutter/src/widgets/framework.dart:1557)
android: I/flutter : #8 _InactiveElements._unmount (packages/flutter/src/widgets/framework.dart:478)
android: I/flutter : #9 _InactiveElements._unmount.<anonymous closure> (packages/flutter/src/widgets/framework.dart:480)
android: I/flutter : #10 ComponentElement.visitChildren (packages/flutter/src/widgets/framework.dart:1090)
android: I/flutter : #11 _InactiveElem