Null check operator is used on a null value when long press a link

[tschiekdev]

Is there an existing issue for this?

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Flutter Quill version

10.7.5

Steps to reproduce

dont know

Expected results

no error

Actual results

Null check operator used on a null value

#0 _TextLineState._longPressLink (package:flutter_quill/src/editor/widgets/text/text_line.dart:656)#1 _TextLineState._getRecognizer. (package:flutter_quill/src/editor/widgets/text/text_line.dart:623) #2 GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:351) #3 LongPressGestureRecognizer._checkLongPressStart (package:flutter/src/gestures/long_press.dart:709) #4 LongPressGestureRecognizer.didExceedDeadline (package:flutter/src/gestures/long_press.dart:610) #5 PrimaryPointerGestureRecognizer.didExceedDeadlineWithEvent (package:flutter/src/gestures/recognizer.dart:731) #6 PrimaryPointerGestureRecognizer.addAllowedPointer. (package:flutter/src/gestures/recognizer.dart:674) #7 _rootRun (dart:async/zone.dart:1391) #8 _CustomZone.run (dart:async/zone.dart:1301) #9 _CustomZone.runGuarded (dart:async/zone.dart:1209) #10 _CustomZone.bindCallbackGuarded. (dart:async/zone.dart:1249) #11 _rootRun (dart:async/zone.dart:1399) #12 _CustomZone.run (dart:async/zone.dart:1301) #13 _CustomZone.bindCallback. (dart:async/zone.dart:1233) #14 Timer._createTimer. (dart:async-patch/timer_patch.dart:18) #15 _Timer._runTimers (dart:isolate-patch/timer_impl.dart:398) #16 _Timer._handleMessage (dart:isolate-patch/timer_impl.dart:429) #17 _RawReceivePort._handleMessage (dart:isolate-patch/isolate_patch.dart:184)

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[EchoEllet]

This line is causing the issue. Need to handle this in a better way without using the null check operator, if we're not sure why then should use assert or throw an exception with a clear message instead of return and then causing unexpected behavior that's more difficult to trace.

This commit is related.

I would avoid using dynamic in Dart (and any other language) when possible which is something that's used in Delta and Attribute, instead manually cast and handle exceptions.

[leonardmatasel-dinova]

Hi @tschiekdev @EchoEllet,

The error occurs when you perform a long press on a piece of text, add a link, then long press again and choose “remove.” After that, performing another long press on the same text triggers the reported error. To reproduce the issue, you need to start with a completely empty field.

The identified fix involves modifying the _longPressLink function in the text_line file. Here’s the updated code:

Future<void> _longPressLink(Node node) async {
  final link = node.style.attributes[Attribute.link.key]!.value!;
  final action = await widget.linkActionPicker(node);
  switch (action) {
    case LinkMenuAction.launch:
      _tapLink(link);
      break;
    case LinkMenuAction.copy:
      Clipboard.setData(ClipboardData(text: link));
      break;
    case LinkMenuAction.remove:
      final range = getLinkRange(node);
      widget.controller
          .formatText(range.start, range.end - range.start, Attribute.link);
      // ADDED CODE
      final recognizer = _linkRecognizers.remove(node);
      recognizer?.dispose();
      // END ADDED CODE
      break;
    case LinkMenuAction.none:
      break;
  }
}

The issue happens because, at line 659 of the text_line file, a class is instantiated that registers a callback, which isn’t properly removed when the link is deleted:

if (isLink && canLaunchLinks) {
  if (isDesktop || widget.readOnly) {
    _linkRecognizers[segment] = TapGestureRecognizer()
      ..onTap = () => _tapNodeLink(segment);
  } else {
    _linkRecognizers[segment] = LongPressGestureRecognizer()
      ..onLongPress = () => _longPressLink(segment);
  }
}

I hope this information is helpful and that the issue will be fixed in the main branch 🚀

Best regards, Leonard