Undefined array key 0 in Drupal\comment\Plugin\Field\FieldWidget\CommentWidget->formElement() (line 71 of core/modules/comment/src/Plugin/Field/FieldWidget/CommentWidget.php).

Nicolas S. → changed the visibility of the branch 3453896-undefined-array-key to hidden.

Nicolas S. → closed merge request !8371

Thanks for reporting

Moving to 11.x as the current development branch, MR will have to be updated as well.

Issue summary should follow standard issue template

There are a test scenario that can be added to show the issue and make sure it doesn't come back.

Thanks.

I updated the summary to match the issue template, as this solved my problem too.

I'm getting this error in a more convoluted scenario; I have three different types of comment in a fieldgroup, rendering on a page where there are also editable fields. I'm pleased to say the proposed change also handled my case and I stopped receiving needless error messages.

Comment fields do not need to have default values and this patch seems to handle the situation well.