Try going into:
C:\FeralHeart\media\particles
and delete any possible file that has the name (something)_01 _02 etc. If you do not have any that isn't the issue and you should leave them be, only delete if there's duplicates.
Also as a sidenote if you didn't know, if you have made a map inside the game that has a portal working from cape, and you export it.
The export will work like a map in cape on it's own! This means that you will have 2 identical maps unless you remove 1 of them. So if you remove the exports thinking the map will be gone, the map in the map maker will still give you a portal in cape, same thing would be the other way around.
If your crashes aren't sorted a fresh install of the game should sort it for you.