Issue 1:
This happens every time I have a dirty form on one tab, move to another tab with the same form and come back.

@MSchrenker commented a test case below to reproduce a similar issue.

flutter: ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
flutter: The following assertion was thrown building NotificationListener<KeepAliveNotification>:
flutter: 'package:flutter/src/rendering/object.dart': Failed assertion: line 2756 pos 14:
flutter: '_debugUltimatePreviousSiblingOf(after, equals: _firstChild)': is not true.
flutter:
flutter: Either the assertion indicates an error in the framework itself, or we should provide substantially
flutter: more information in this error message to help you determine and fix the underlying cause.
flutter: In either case, please report this assertion by filing a bug on GitHub:
flutter: https://github.com/flutter/flutter/issues/new
flutter:
flutter: When the exception was thrown, this was the stack:
flutter: #2 _RenderSliverMultiBoxAdaptor&RenderSliver&ContainerRenderObjectMixin._insertIntoChildList (package:flutter/src/rendering/object.dart)
flutter: #3 _RenderSliverMultiBoxAdaptor&RenderSliver&ContainerRenderObjectMixin.insert (package:flutter/src/rendering/object.dart:2790:5)
flutter: #4 RenderSliverMultiBoxAdaptor.insert (package:flutter/src/rendering/sliver_multi_box_adaptor.dart:209:11)
flutter: #5 SliverMultiBoxAdaptorElement.insertChildRenderObject (package:flutter/src/widgets/sliver.dart:863:18)
flutter: #6 RenderObjectElement.attachRenderObject (package:flutter/src/widgets/framework.dart:4513:35)
flutter: #7 RenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4279:5)
flutter: #8 SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4653:11)
flutter: #9 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2907:14)
flutter: #10 Element.updateChild (package:flutter/src/widgets/framework.dart:2710:12)
flutter: #11 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #12 Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #13 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3622:5)
flutter: #14 ComponentElement.mount (package:flutter/src/widgets/framework.dart:3617:5)
flutter: #15 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2907:14)
flutter: #16 Element.updateChild (package:flutter/src/widgets/framework.dart:2710:12)
flutter: #17 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #18 Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #19 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3622:5)
flutter: #20 ComponentElement.mount (package:flutter/src/widgets/framework.dart:3617:5)
flutter: #21 ParentDataElement.mount (package:flutter/src/widgets/framework.dart:3955:11)
flutter: #22 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2907:14)
flutter: #23 Element.updateChild (package:flutter/src/widgets/framework.dart:2710:12)
flutter: #24 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #25 Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #26 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3622:5)
flutter: #27 StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:3769:11)
flutter: #28 ComponentElement.mount (package:flutter/src/widgets/framework.dart:3617:5)
flutter: #29 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2907:14)
flutter: #30 Element.updateChild (package:flutter/src/widgets/framework.dart:2710:12)
flutter: #31 SliverMultiBoxAdaptorElement.updateChild (package:flutter/src/widgets/sliver.dart:744:36)
flutter: #32 SliverMultiBoxAdaptorElement.performRebuild (package:flutter/src/widgets/sliver.dart:702:34)
flutter: #33 SliverMultiBoxAdaptorElement.update (package:flutter/src/widgets/sliver.dart:671:7)
flutter: #34 Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #35 RenderObjectElement.updateChildren (package:flutter/src/widgets/framework.dart:4379:32)
flutter: #36 MultiChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4769:17)
flutter: #37 _ViewportElement.update (package:flutter/src/widgets/viewport.dart:192:11)
flutter: #38 Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #39 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #40 Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #41 ProxyElement.update (package:flutter/src/widgets/framework.dart:3909:5)
flutter: #42 Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #43 SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4661:14)
flutter: #44 Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #45 SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4661:14)
flutter: #46 Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #47 SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4661:14)
flutter: #48 Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #49 SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4661:14)
flutter: #50 Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #51 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #52 Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #53 StatefulElement.update (package:flutter/src/widgets/framework.dart:3799:5)
flutter: #54 Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #55 SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4661:14)
flutter: #56 Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #57 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #58 Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #59 StatefulElement.update (package:flutter/src/widgets/framework.dart:3799:5)
flutter: #60 Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #61 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #62 Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #63 StatelessElement.update (package:flutter/src/widgets/framework.dart:3702:5)
flutter: #64 Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #65 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #66 Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #67 StatefulElement.update (package:flutter/src/widgets/framework.dart:3799:5)
flutter: #68 Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #69 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #70 Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #71 StatelessElement.update (package:flutter/src/widgets/framework.dart:3702:5)
flutter: #72 Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #73 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #74 Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #75 StatefulElement.update (package:flutter/src/widgets/framework.dart:3799:5)
flutter: #76 Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #77 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #78 Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #79 ProxyElement.update (package:flutter/src/widgets/framework.dart:3909:5)
flutter: #80 Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #81 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #82 Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #83 ProxyElement.update (package:flutter/src/widgets/framework.dart:3909:5)
flutter: #84 Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #85 RenderObjectElement.updateChildren (package:flutter/src/widgets/framework.dart:4379:32)
flutter: #86 MultiChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4769:17)
flutter: #87 Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #88 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #89 Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #90 StatefulElement.update (package:flutter/src/widgets/framework.dart:3799:5)
flutter: #91 Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #92 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #93 Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #94 ProxyElement.update (package:flutter/src/widgets/framework.dart:3909:5)
flutter: #95 Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #96 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #97 Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #98 StatefulElement.update (package:flutter/src/widgets/framework.dart:3799:5)
flutter: #99 Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #100 SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4661:14)
flutter: #101 Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #102 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #103 Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #104 StatelessElement.update (package:flutter/src/widgets/framework.dart:3702:5)
flutter: #105 Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #106 SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4661:14)
flutter: #107 Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #108 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #109 Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #110 StatefulElement.update (package:flutter/src/widgets/framework.dart:3799:5)
flutter: #111 Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #112 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #113 Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #114 StatefulElement.update (package:flutter/src/widgets/framework.dart:3799:5)
flutter: #115 Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #116 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #117 Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #118 ProxyElement.update (package:flutter/src/widgets/framework.dart:3909:5)
flutter: #119 Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #120 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #121 Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #122 ProxyElement.update (package:flutter/src/widgets/framework.dart:3909:5)
flutter: #123 Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #124 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #125 Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #126 StatefulElement.update (package:flutter/src/widgets/framework.dart:3799:5)
flutter: #127 Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #128 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #129 Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #130 BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2242:33)
flutter: #131 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&RendererBinding&WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:626:20)
flutter: #132 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:208:5)
flutter: #133 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:990:15)
flutter: #134 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:930:9)
flutter: #135 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:842:5)
flutter: #136 _invoke (dart:ui/hooks.dart:120:13)
flutter: #137 _drawFrame (dart:ui/hooks.dart:109:3)
flutter: (elided 2 frames from class _AssertionError)
flutter: ════════════════════════════════════════════════════════════════════════════════════════════════════
flutter: Another exception was thrown: 'package:flutter/src/rendering/object.dart': Failed assertion: line 2756 pos 14: '_debugUltimatePreviousSiblingOf(after, equals: _firstChild)': is not true.
flutter: Another exception was thrown: 'package:flutter/src/rendering/object.dart': Failed assertion: line 2756 pos 14: '_debugUltimatePreviousSiblingOf(after, equals: _firstChild)': is not true.
flutter: Another exception was thrown: 'package:flutter/src/rendering/object.dart': Failed assertion: line 2756 pos 14: '_debugUltimatePreviousSiblingOf(after, equals: _firstChild)': is not true.
flutter: Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3497 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
flutter: Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3497 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
flutter: Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3497 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
flutter: Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3497 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
flutter: Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3497 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
flutter: Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3497 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
flutter: Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3497 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
flutter: Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3497 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
flutter: Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3497 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
flutter: Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3497 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
flutter: Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3497 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
flutter: Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3497 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
flutter: Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3497 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
flutter: Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3497 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
flutter: Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3497 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
flutter: Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3497 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
flutter: Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3497 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
flutter: Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3497 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
flutter: Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3497 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
flutter: Another exception was thrown: type 'RenderErrorBox' is not a subtype of type 'RenderSemanticsGestureHandler'

Issue 2:
Steps to Reproduce

I have a PageView that contains the top level widgets for my app, with switching between them controlled by a BottomNavBar. As per @Hixie's advice in the chat, I am adding AutomaticKeepAliveClientMixin to these top level widgets so the PageView won't recycle them and will preserve state. After I added this to the main widget that contains a network loaded ListView, on occasion when switching back to this ListView from another tab I get this failed assertion in the framework.

Logs

══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
The following assertion was thrown building NotificationListener<KeepAliveNotification>:
'package:flutter/src/rendering/object.dart': Failed assertion: line 3031 pos 14:
'_debugUltimatePreviousSiblingOf(after, equals: _firstChild)': is not true.
Either the assertion indicates an error in the framework itself, or we should provide substantially
more information in this error message to help you determine and fix the underlying cause.
In either case, please report this assertion by filing a bug on GitHub:
https://github.com/flutter/flutter/issues/new
When the exception was thrown, this was the stack:
#2 RenderSliver&ContainerRenderObjectMixin._insertIntoChildList (package:flutter/src/rendering/object.dart:3031:14)
#3 RenderSliver&ContainerRenderObjectMixin.insert (package:flutter/src/rendering/object.dart:3065:5)
#4 RenderSliverMultiBoxAdaptor.insert (package:flutter/src/rendering/sliver_multi_box_adaptor.dart:193:17)
#5 SliverMultiBoxAdaptorElement.insertChildRenderObject (package:flutter/src/widgets/sliver.dart:840:18)
#6 RenderObjectElement.attachRenderObject (package:flutter/src/widgets/framework.dart:4380:35)
#7 RenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4151:5)
#8 SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4515:16)
#9 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2882:14)
#10 Element.updateChild (package:flutter/src/widgets/framework.dart:2685:12)
#11 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
#12 Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
#13 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3514:5)
#14 ComponentElement.mount (package:flutter/src/widgets/framework.dart:3509:5)
#15 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2882:14)
#16 Element.updateChild (package:flutter/src/widgets/framework.dart:2685:12)
#17 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
#18 Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
#19 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3514:5)
#20 ComponentElement.mount (package:flutter/src/widgets/framework.dart:3509:5)
#21 ParentDataElement.mount (package:flutter/src/widgets/framework.dart:3827:16)
#22 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2882:14)
#23 Element.updateChild (package:flutter/src/widgets/framework.dart:2685:12)
#24 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
#25 Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
#26 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3514:5)
#27 StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:3652:22)
#28 ComponentElement.mount (package:flutter/src/widgets/framework.dart:3509:5)
#29 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2882:14)
#30 Element.updateChild (package:flutter/src/widgets/framework.dart:2685:12)
#31 SliverMultiBoxAdaptorElement.performRebuild (package:flutter/src/widgets/sliver.dart:696:34)
#32 SliverMultiBoxAdaptorElement.update (package:flutter/src/widgets/sliver.dart:665:7)
#33 Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
#34 RenderObjectElement.updateChildren (package:flutter/src/widgets/framework.dart:4250:32)
#35 MultiChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4631:17)
#36 _ViewportElement.update (package:flutter/src/widgets/viewport.dart:150:17)
#37 Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
#38 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
#39 Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
#40 ProxyElement.update (package:flutter/src/widgets/framework.dart:3781:5)
#41 Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
#42 SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4523:14)
#43 Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
#44 SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4523:14)
#45 Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
#46 SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4523:14)
#47 Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
#48 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
#49 Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
#50 StatefulElement.update (package:flutter/src/widgets/framework.dart:3671:5)
#51 Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
#52 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
#53 Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
#54 StatefulElement.update (package:flutter/src/widgets/framework.dart:3671:5)
#55 Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
#56 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
#57 Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
#58 StatelessElement.update (package:flutter/src/widgets/framework.dart:3596:5)
#59 Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
#60 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
#61 Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
#62 StatefulElement.update (package:flutter/src/widgets/framework.dart:3671:5)
#63 Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
#64 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
#65 Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
#66 ProxyElement.update (package:flutter/src/widgets/framework.dart:3781:5)
#67 Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
#68 RenderObjectElement.updateChildren (package:flutter/src/widgets/framework.dart:4250:32)
#69 MultiChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4631:17)
#70 Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
#71 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
#72 Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
#73 ProxyElement.update (package:flutter/src/widgets/framework.dart:3781:5)
#74 Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
#75 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
#76 Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
#77 StatefulElement.update (package:flutter/src/widgets/framework.dart:3671:5)
#78 Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
#79 SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4523:14)
#80 Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
#81 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
#82 Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
#83 StatelessElement.update (package:flutter/src/widgets/framework.dart:3596:5)
#84 Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
#85 SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4523:14)
#86 Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
#87 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
#88 Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
#89 StatefulElement.update (package:flutter/src/widgets/framework.dart:3671:5)
#90 Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
#91 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
#92 Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
#93 StatefulElement.update (package:flutter/src/widgets/framework.dart:3671:5)
#94 Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
#95 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
#96 Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
#97 ProxyElement.update (package:flutter/src/widgets/framework.dart:3781:5)
#98 Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
#99 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
#100 Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
#101 ProxyElement.update (package:flutter/src/widgets/framework.dart:3781:5)
#102 Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
#103 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
#104 Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
#105 StatefulElement.update (package:flutter/src/widgets/framework.dart:3671:5)
#106 Element.updateChild (package:flutter/src/widgets/framework.dart:2674:15)
#107 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3546:16)
#108 Element.rebuild (package:flutter/src/widgets/framework.dart:3435:5)
#109 BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2260:33)
#110 BindingBase&SchedulerBinding&GestureBinding&ServicesBinding&RendererBinding&WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:503:20)
#111 BindingBase&SchedulerBinding&GestureBinding&ServicesBinding&RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:189:5)
#112 BindingBase&SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:695:15)
#113 BindingBase&SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:643:9)
#114 _invoke (file:///b/build/slave/Mac_Engine/build/src/flutter/lib/ui/hooks.dart:86)
#115 _drawFrame (file:///b/build/slave/Mac_Engine/build/src/flutter/lib/ui/hooks.dart:75)
(elided 2 frames from class _AssertionError)
════════════════════════════════════════════════════════════════════════════════════════════════════
Another exception was thrown: 'package:flutter/src/rendering/object.dart': Failed assertion: line 3031 pos 14: '_debugUltimatePreviousSiblingOf(after, equals: _firstChild)': is not true.
Another exception was thrown: 'package:flutter/src/rendering/object.dart': Failed assertion: line 3031 pos 14: '_debugUltimatePreviousSiblingOf(after, equals: _firstChild)': is not true.
Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3437 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3437 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3437 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3437 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3437 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3437 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3437 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3437 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3437 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3437 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3437 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3437 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3437 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3437 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.

Analyzing /Users/matt/code/flutter/kudos...
lint • Don't import implementation files from another package at lib/feed.dart:5:8 • implementation_imports
lint • Close instances of `dart.core.Sink` at lib/feed.dart:26:26 • close_sinks
lint • Don't explicitly initialize variables to null at lib/loading_list_view.dart:23:5 • avoid_init_to_null
lint • Don't import implementation files from another package at lib/post.dart:3:8 • implementation_imports
hint • Unused import at lib/application.dart:4:8 • unused_import
hint • Unused import at lib/feed.dart:2:8 • unused_import
hint • Unused import at lib/feed.dart:5:8 • unused_import
hint • Unused import at lib/feed.dart:7:8 • unused_import
hint • Unused import at lib/feed.dart:12:8 • unused_import
hint • Unused import at lib/feed.dart:13:8 • unused_import
hint • This method overrides a method annotated as @mustCallSuper in 'State', but does not invoke the overridden method at lib/feed.dart:29:8 • must_call_super
hint • This method overrides a method annotated as @mustCallSuper in 'State', but does not invoke the overridden method at lib/feed.dart:40:8 • must_call_super
hint • The type parameter 'widgetAdapter' is annotated with @required but only named parameters without default value can be annotated with it at lib/loading_list_view.dart:23:5 • invalid_required_param
hint • Unused import at lib/main.dart:6:8 • unused_import
hint • The value of the field '_counter' isn't used at lib/main.dart:56:7 • unused_field
hint • This method overrides a method annotated as @mustCallSuper in 'State', but does not invoke the overridden method at lib/main.dart:63:8 • must_call_super
hint • This method overrides a method annotated as @mustCallSuper in 'State', but does not invoke the overridden method at lib/main.dart:71:8 • must_call_super
hint • The method '_incrementCounter' isn't used at lib/main.dart:76:8 • unused_element
hint • Unused import at lib/post.dart:7:8 • unused_import
hint • This class inherits from a class marked as @immutable, and therefore should be immutable (all instance fields must be final) at lib/post.dart:10:7 • must_be_immutable
hint • This class inherits from a class marked as @immutable, and therefore should be immutable (all instance fields must be final) at lib/post.dart:34:7 • must_be_immutable
hint • The value of the local variable 'plainText' isn't used at lib/post.dart:71:10 • unused_local_variable
hint • This class inherits from a class marked as @immutable, and therefore should be immutable (all instance fields must be final) at lib/post.dart:112:7 • must_be_immutable
hint • This class inherits from a class marked as @immutable, and therefore should be immutable (all instance fields must be final) at lib/post.dart:160:7 • must_be_immutable
hint • This class inherits from a class marked as @immutable, and therefore should be immutable (all instance fields must be final) at lib/profile.dart:10:7 • must_be_immutable
hint • This method overrides a method annotated as @mustCallSuper in 'State', but does not invoke the overridden method at lib/profile.dart:27:10 • must_call_super
hint • This class inherits from a class marked as @immutable, and therefore should be immutable (all instance fields must be final) at lib/profile.dart:145:7 • must_be_immutable
hint • The class '_KudosEarned' isn't used at lib/profile.dart:218:7 • unused_element
hint • Unused import at lib/send_photo.dart:5:8 • unused_import
hint • Unused import at lib/usersearch.dart:6:8 • unused_import
hint • Unused import at lib/usersearch.dart:7:8 • unused_import
hint • This method overrides a method annotated as @mustCallSuper in 'State', but does not invoke the overridden method at lib/usersearch.dart:25:10 • must_call_super
32 issues found.

Flutter Doctor

[✓] Flutter (on Mac OS X 10.12.6 16G29, locale en-US, channel alpha)
• Flutter at /Users/matt/code/flutter/flutter
• Framework revision b156a0f054 (3 weeks ago), 2017-08-11 22:01:40 -0700
• Engine revision fef7d827d6
• Tools Dart version 1.25.0-dev.9.0

[✓] Android toolchain - develop for Android devices (Android SDK 25.0.3)
• Android SDK at /Users/matt/code/android/android
• Platform android-25, build-tools 25.0.3
• Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
• Java version OpenJDK Runtime Environment (build 1.8.0_112-release-b06)

[✓] iOS toolchain - develop for iOS devices (Xcode 8.3.3)
• Xcode at /Applications/Xcode.app/Contents/Developer
• Xcode 8.3.3, Build version 8E3004b
• ios-deploy 1.9.1
• CocoaPods version 1.3.1

[✓] Android Studio (version 2.3)
• Android Studio at /Applications/Android Studio.app/Contents
• Java version OpenJDK Runtime Environment (build 1.8.0_112-release-b06)

[✓] IntelliJ IDEA Ultimate Edition (version 2017.2.2)
• Flutter plugin version 16.0
• Dart plugin version 172.3757.55

[✓] Connected devices
• iPhone 6s • 3DF999CB-1CD6-4649-8187-DDEFBDB14DFA • ios • iOS 10.3 (simulator)

For more information about diagnosing and reporting Flutter bugs, please see https://flutter.io/bug-reports/.