You might've gotten too much files for FeralHeart or FeralHeart+ and i find this strange. Maybe just a virus on your FeralHeart/Computer but you might just be missing a few files like Zaruque said. I suggest Re-downloading FeralHeart/FeralHeart+ then re-install it. Though, if you have a lot of files then you also might wanna delete some if you already tried re-downloading then re-installing FeralHeart/FeralHeart+ and i would suggest the highest numbers like maps or objects.