Null check operator used on a null value
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- Dart
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Description
**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
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by inspecting _LineChartState._handleBuiltInTouch in line_chart.dart and the touch-event flow through render_base_chart.dart. Trace which value can be null during the production long-press path, then verify the fix against the existing project checks; done means the reported null-check exception no longer occurs during line-chart touch handling.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- dart, flutter
- Domain
- frontend, mobile-dev
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 35/100