Seems like that problem should probably either be prevented or have a more useful error message in any case.
Yes; I need to know what caused it first. But if that's it, then I know where to put the check
Whoops. Didn't notice that. P.s. Is there a way to make animations go slower than 15 FPS? At that speed it still looks odd.
15 FPS is just the preview speed. It will only actually run at that speed if your game is only running at 15 FPS. I don't think you want your game running that slowly, and certainly not even slower than that. If you want the animation to run more slowly, you need to change the repeat count of the frames. If you select all the frames and then increase the repeat count (it will increase that value for all selected frames), it will flip through the selected frames more slowly. Changing repeat count from 1 to 2 will make the animation run half as fast. Changing it from 1 to 3 will make it run 1/3rd as fast, etc.