Null check operator used on a null value

[ozzy1873]

Describe the bug
Non-fatal Exception: io.flutter.plugins.firebase.crashlytics.FlutterError: Null check operator used on a null value. Error thrown Instance of 'ErrorDescription'.
at State.setState(framework.dart:1129)
at _LineChartState._handleBuiltInTouch(line_chart.dart:108)
at RenderBaseChart._notifyTouchEvent(render_base_chart.dart:140)
at RenderBaseChart.initGestureRecognizers.(render_base_chart.dart:76)
at LongPressGestureRecognizer._checkLongPressMoveUpdate.(long_press.dart:756)
at GestureRecognizer.invokeCallback(recognizer.dart:198)
at LongPressGestureRecognizer._checkLongPressMoveUpdate(long_press.dart:756)
at LongPressGestureRecognizer.handlePrimaryPointer(long_press.dart:652)
at PrimaryPointerGestureRecognizer.handleEvent(recognizer.dart:563)
at PointerRouter._dispatch(pointer_router.dart:94)
at PointerRouter._dispatchEventToRoutes.(pointer_router.dart:139)
at _LinkedHashMapMixin.forEach(_LinkedHashMapMixin.java)
at PointerRouter._dispatchEventToRoutes(pointer_router.dart:137)
at PointerRouter.route(pointer_router.dart:123)
at GestureBinding.handleEvent(binding.dart:445)
at GestureBinding.dispatchEvent(binding.dart:425)
at RendererBinding.dispatchEvent(binding.dart:329)
at GestureBinding._handlePointerEventImmediately(binding.dart:380)
at GestureBinding.handlePointerEvent(binding.dart:344)
at GestureBinding._flushPointerEventQueue(binding.dart:302)
at GestureBinding._handlePointerDataPacket(binding.dart:285)

To Reproduce
I do not know how to reproduce this issue. It happens in the field in production.

Versions
Flutter 3.0.5
fl_chart 0.55.0

[imaNNeo]

I couldn't find the problem. Any more details?

[robindijkhof]

I don't think this is related to this lib. flutter/flutter#81684

[HenrikSunvigo]

We may have to check whether this State object is currently in a tree.
It could be fixed by using
if (!mounted) return;
before using setState in _handleBuiltInTouch()

[hm122]

Facing the same issue. Was anyone able to fix this?

[imaNNeo]

Any reproducible code?

[hm122]

Unfortunately no. I'm not able to reproduce it locally. Stacktrace from sentry looks similar as the one above:

_CastError: Null check operator used on a null value
  State.setState (framework.dart:1129)
  _LineChartState._handleBuiltInTouch (line_chart.dart:101)
  _LineChartState._handleBuiltInTouch (line_chart.dart:94)
  RenderBaseChart._notifyTouchEvent (render_base_chart.dart:140)
  RenderBaseChart.initGestureRecognizers.<T> (render_base_chart.dart:68)
  GestureRecognizer.invokeCallback (recognizer.dart:198)
  TapGestureRecognizer.handleTapCancel (tap.dart:636)
  BaseTapGestureRecognizer._checkCancel (tap.dart:303)
  BaseTapGestureRecognizer.rejectGesture (tap.dart:280)
  GestureArenaManager._resolveInFavorOf (arena.dart:262)
  GestureArenaManager._resolve (arena.dart:223)
  GestureArenaEntry.resolve (arena.dart:53)
  OneSequenceGestureRecognizer.resolve (recognizer.dart:306)
  LongPressGestureRecognizer.resolve (long_press.dart:834)
  LongPressGestureRecognizer.didExceedDeadline (long_press.dart:612)
  PrimaryPointerGestureRecognizer.didExceedDeadlineWithEvent (recognizer.dart:591)
  PrimaryPointerGestureRecognizer.addAllowedPointer.<T> (recognizer.dart:535)
  _rootRun (zone.dart:1418)
  _rootRun (zone.dart:1417)
  _CustomZone.run (zone.dart:1328)
  _CustomZone.runGuarded (zone.dart:1236)
  _CustomZone.bindCallbackGuarded.<T> (zone.dart:1276)
  _rootRun (zone.dart:1426)
  _rootRun (zone.dart:1417)
  _CustomZone.run (zone.dart:1328)
  _CustomZone.bindCallback.<T> (zone.dart:1260)
  TickerFuture.whenCompleteOrCancel.thunk (ticker.dart:407)
  _Timer._runTimers (timer_impl.dart:398)
  _Timer._handleMessage (timer_impl.dart:429)
  _Timer._handleMessage (timer_impl.dart:419)
  _RawReceivePortImpl._handleMessage (isolate_patch.dart:192)

[imaNNeo]

_LineChartState._handleBuiltInTouch (line_chart.dart:101)

I think you are right.
In a normal situation, touchCallback should not be called when the widget is disposed of. But as we handle gestures, it might take a little time to get a gesture result and in this little time, our widget might be disposed.

So @HenrikSunvigo can you please add your solution in all of the chart types?

[ozzy1873]

Yes, @HenrikSunvigo is correct. You need to check if the widget is mounted before calling setState.

[imaNNeo]

We did the if (mounted) check in 0.62.0.
Please check it out and let me know whether it is fixed or not.

[btrautmann]

I can't speak to this exact issue, but I'm having a similar error on version 0.63.0, and it seems to be this line. In my logs I'm seeing the user navigate away from and back to the chart, but because the chart shows up on multiple screens, I can't say for sure whether it was the screen that would have been disposed that caused the issue.

MediaQuery._of (media_query.dart:1018)
MediaQuery.of (media_query.dart:1013)
LineChartLeaf.createRenderObject (line_chart_renderer.dart:27)
RenderObjectElement.mount (framework.dart:5932)
Element.inflateWidget (framework.dart:3971)
Element.updateChild (framework.dart:3708)
SingleChildRenderObjectElement.mount (framework.dart:6435)
Element.inflateWidget (framework.dart:3971)
Element.updateChild (framework.dart:3708)
SingleChildRenderObjectElement.mount (framework.dart:6435)
Element.inflateWidget (framework.dart:3971)
Element.updateChild (framework.dart:3708)
SingleChildRenderObjectElement.mount (framework.dart:6435)
Element.inflateWidget (framework.dart:3971)
Element.updateChild (framework.dart:3708)
ComponentElement.performRebuild (framework.dart:5111)
Element.rebuild (framework.dart:4805)
ComponentElement._firstBuild (framework.dart:5068)
ComponentElement.mount (framework.dart:5062)
Element.inflateWidget (framework.dart:3971)
MultiChildRenderObjectElement.inflateWidget (framework.dart:6570)
MultiChildRenderObjectElement.mount (framework.dart:6582)
Element.inflateWidget (framework.dart:3971)
Element.updateChild (framework.dart:3708)
_LayoutBuilderElement._layout.layoutCallback (layout_builder.dart:135)
BuildOwner.buildScope (framework.dart:2720)
_LayoutBuilderElement._layout (layout_builder.dart:153)
RenderObject.invokeLayoutCallback.<fn> (object.dart:2506)
PipelineOwner._enableMutationsToDirtySubtrees (object.dart:1062)
RenderObject.invokeLayoutCallback (object.dart:2506)
RenderConstrainedLayoutBuilder.rebuildIfNecessary (layout_builder.dart:228)
_RenderLayoutBuilder.performLayout (layout_builder.dart:313)
RenderObject.layout (object.dart:2395)
RenderBox.layout (box.dart:2386)
RenderPadding.performLayout (shifted_box.dart:238)
RenderObject.layout (object.dart:2395)
RenderBox.layout (box.dart:2386)
ChildLayoutHelper.layoutChild (layout_helper.dart:52)
RenderStack._computeSize (stack.dart:580)
RenderStack.performLayout (stack.dart:607)
RenderObject.layout (object.dart:2395)
RenderBox.layout (box.dart:2386)
RenderAspectRatio.performLayout (proxy_box.dart:594)
RenderObject.layout (object.dart:2395)
RenderBox.layout (box.dart:2386)
ChildLayoutHelper.layoutChild (layout_helper.dart:52)
RenderFlex._computeSizes (flex.dart:808)
RenderFlex.performLayout (flex.dart:903)
RenderObject.layout (object.dart:2395)
RenderBox.layout (box.dart:2386)
RenderPadding.performLayout (shifted_box.dart:238)
RenderObject.layout (object.dart:2395)
RenderBox.layout (box.dart:2386)
RenderProxyBoxMixin.performLayout (proxy_box.dart:122)
RenderObject.layout (object.dart:2395)
RenderBox.layout (box.dart:2386)
RenderProxyBoxMixin.performLayout (proxy_box.dart:122)
_RenderCustomClip.performLayout (proxy_box.dart:1449)
RenderObject.layout (object.dart:2395)
RenderBox.layout (box.dart:2386)
_MeasurementView.performLayout (screenshot.dart:394)
RenderObject._layoutWithoutResize (object.dart:2234)
PipelineOwner.flushLayout (object.dart:1016)
ScreenshotController.longWidgetToUiImage (screenshot.dart:323)
ScreenshotController.captureFromLongWidget (screenshot.dart:287)
ShareChartScreen.build.<fn> (share_chart_screen.dart:53)
_InkResponseState.handleTap (ink_well.dart:1154)
GestureRecognizer.invokeCallback (recognizer.dart:275)
TapGestureRecognizer.handleTapUp (tap.dart:654)
BaseTapGestureRecognizer._checkUp (tap.dart:311)
BaseTapGestureRecognizer.handlePrimaryPointer (tap.dart:244)
PrimaryPointerGestureRecognizer.handleEvent (recognizer.dart:630)
PointerRouter._dispatch (pointer_router.dart:98)
PointerRouter._dispatchEventToRoutes.<fn> (pointer_router.dart:143)
_LinkedHashMapMixin.forEach (dart:collection)
PointerRouter._dispatchEventToRoutes (pointer_router.dart:141)
PointerRouter.route (pointer_router.dart:127)
GestureBinding.handleEvent (binding.dart:465)
GestureBinding.dispatchEvent (binding.dart:445)
RendererBinding.dispatchEvent (binding.dart:331)
GestureBinding._handlePointerEventImmediately (binding.dart:400)
GestureBinding.handlePointerEvent (binding.dart:363)
GestureBinding._flushPointerEventQueue (binding.dart:320)
GestureBinding._handlePointerDataPacket (binding.dart:293)

[imaNNeo]

We can add a fallback value of 1.0 for the line that you mentioned.

fl_chart/lib/src/chart/line_chart/line_chart_renderer.dart

Line 27 in 04b18d2

MediaQuery.of(context).textScaleFactor,