Notice on the form display settings page when we remove the paragraph types from the field settings

Hello,

Thank for your wonderful module. I'm glad I'm using it.

I noticed one issue when using this module on the form display settings page of an content type using the "default paragraph" widget.

Notice: Undefined index: <paragraph type> in /var/www/html/modules/contrib/default_paragraphs/src/Plugin/Field/FieldWidget/DefaultParagraphsWidget.php on line 220

The steps to reproduce this issue are:

1. Create a paragraph type
2. Add a field of type Entity reference revisions to a content type
3. In the field settings, include the paragraph type we created in step 1 and save the field
4. Go to the form display settings of the field and use the Default Paragraph widget for that field we created in step 2, save the settings
5. Go to the field settings page and remove the paragraph type from the field, save the field
6. Go to the form display settings page that we visited in step 4 again
7. Observe the PHP notice.

Clearing the cache doesn't seem to fix the issue. A serious repercussion of this notice is that we can't open the default paragraph settings widget ever again. I'm working on a patch for this. Let me know if someone has any idea.