Automation chain editor should still be available after a "required value" validation error

Steps to reproduce:

1. In an automation chain, add the Fetch > Document operation (or any other operation with a required value) but don't fill the value.
2. Click on Switch editor.
   -> A validation error is displayed. But no editor is displayed anymore, so user cannot fix the error. The only way to have an editor displayed is to click on Discard changes.