AssertionError when dropping a procedure with a parameter

[MelanieLam]

The bug occurs when creating a scene procedure with a parameter. If the procedure is already in use, it has to be updated, OK. If you try to drag another invocation of the procedure, the drop sometimes generates an AssertionError. The Queen pops up. The drag and drop action is interrupted. I tell students to save and relaunch Alice. Nothing bad seems to happen after.

Here are the steps to reproduce the error:

1. Launch Alice. Create a new scene.
2. Add a scene procedure.
3. Switch back to myFirstMethod and call the new procedure.
4. Switch back to the new procedure and add a parameter. Tick the box "I understand I need to update the invocations to this procedure."
5. Switch back to myFirstMethod.
6. Fix the invocation (or not, it doesn't matter)
7. Drag a new invocation of the procedure, and drop it above the existing procedure invocation.
   This generates an "Assertion Error."

[dabeshouse]

I followed these steps and the stack generated is a match for Planning bug 464 so I am closing that as dup of this and updating the Jira search where it is one of our more frequently reported issues.