Preconditions:

Need to be tested on prod and dev mode.

Steps:

1. Configure yaml file following instructions in PR: https://github.com/ibexa/page-builder/pull/391
2. Go to Page builder
3. Drag and drop Campaign block

Actual result:

Error 500 is displayed in console, but there is no notification displayed. Instead of it block is blinking. See attachment, please.

Expected result:

User should be informed in both modes: dev and prod about the issue.