Fix vanilla rare spring ball crash

[strotlog]

This crash hit a runner in a tournament race of the recent rando tournament. Almost nobody had ever heard of it.

To show the bug, you have to be turning off spring ball while landing in morph with a bounce and dust particles. But it's hard to make it happen (perhaps the frame window is small).

Thanks to Kingofthehill476 for getting a save state of it for me since I wanted to find a fix for this. The code is quite simple.

[flohgh]

thanks strotlog :)