Studio crashes when adding type to the same type

[standeren]

In the data modeling tool, if adding a type to the same type that is in use in the schema editor, we get a circular dependency and Studio will crash.

We should validate if this is the case in frontend and terminate the action before the request is sent to backend. Some sort of feedback that this action is illegal should be done.

Alternatives:

1. Disable dropping the type inside an element of the same type and add a tooltip saying why this is not allowed
2. Allow to drop but terminate before the action is handled, and give a message in a toaster.
3. Allow to drop but terminate before the action is handled, and give a message in a browser native alert.