Prevent infinite recursion in rock's grab and ungrab scripts

[tobbi]

This prevents #2906 from happening, however: It also creates infinite flipping and unflipping and I haven't figured out the cause yet. That's why I'm marking it as a draft. If anyone has any idea, go ahead.

[weluvgoatz]

I think the PR is fine; I just set a script like this in order to prevent it from running infinitely:

[weluvgoatz]

However this PR does fix the crash. Thank you!!!!

[tobbi]

I'd really like to fix the flickering issue as well so that it only flips once.

[weluvgoatz]

Not sure if possible since the script seems to run every frame while the rock is being held, rather than just when you first hold it.

[tobbi]

I think the solution might be easier than I initially thought.