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DragGestureRecognizer.acceptGesture null check operator used on a null value #112403
Description
Framework crash from internal b/249091367
UnknownError: Null check operator used on a null value
at DragGestureRecognizer.acceptGesture(monodrag.dart:334)
at GestureArenaManager._resolveByDefault(arena.dart:251)
at GestureArenaManager._tryToResolveArena.<anonymous closure>(arena.dart:232)
at _rootRun(zone.dart:1418)
at _rootRun(zone.dart:1417)
at _CustomZone.run(zone.dart:1328)
at _CustomZone.runGuarded(zone.dart:1236)
at _CustomZone.bindCallbackGuarded.<anonymous closure>(zone.dart:1276)
at _rootRun(zone.dart:1426)
at _rootRun(zone.dart:1417)
at _CustomZone.run(zone.dart:1328)
at _CustomZone.runGuarded(zone.dart:1236)
at _CustomZone.bindCallbackGuarded.<anonymous closure>(zone.dart:1276)
at _microtaskLoop(schedule_microtask.dart:40)
at _startMicrotaskLoop(schedule_microtask.dart:49)
at _startMicrotaskLoop(schedule_microtask.dart:44)
Although the line numbers are different (I'm not sure the exact framework version used in the app this stacktrace is from), I'm pretty sure it's this line: https://github.com/flutter/flutter/blob/master/packages/flutter/lib/src/gestures/monodrag.dart#L367
final Duration timestamp = _lastPendingEventTimestamp!;It's difficult to reason about how we got into this state, but maybe the easiest fix would be to just let _checkStart(timestamp, pointer) be a no-op when timestamp == null, WDYT @dkwingsmt?
Activity
tarobins commentedon Dec 22, 2022
DragStartDetails.sourceTimeStamp can be null, so the timestamp parameter to _checkStart can be null, so there is no need to unwrap _lastPendingEventTimestamp.
Avoid unnecessary unwrap of `_lastPendingEventTimestamp` which someti…
Avoid unnecessary unwrap of `_lastPendingEventTimestamp` which someti…
Fix for flutter#112403 and b/249091367
Fix for #112403 and b/249091367 (#121615)
github-actions commentedon Mar 14, 2023
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