Undefined array key "fences_field_items_wrapper_classes"

I can confirm I have the same issue on my side.

It seems to happen only when you set a "Field items Wrapper Tag". The summary presented in the Manage Display page is empty and the error mentionned by liliplanet appears.

Issue is here:

'fences_field_wrapper_tag' => t('Field items wrapper tag: %field_items_wrapper_tag', ['%field_items_wrapper_tag' => $fencesSettings['fences_field_items_wrapper_tag']]),
      'fences_field_wrapper_classes' => t('Field items wrapper classes: %field_items_wrapper_classes', ['%field_items_wrapper_classes' => $fencesSettings['fences_field_items_wrapper_classes']]),

We are missing "items" for items_wrapper_tag and items_wrapper_classes in array keys.

Thanks for the report, I'm on it!

Regression from 📌 Do we miss explode() calls for fences_field_classes, fences_label_classes, fences_field_items_wrapper_classes Active

Please check, if this fixes the issue. I assume code-wise that the wrapper attribute is still being set correctly? Otherwise, tests should have failed.

So this was only a notice, nothing really broken...?

Okay maybe wasn't even a regression, but from another issue where the summary was added recently.