Well, my /help crash came back after testing for other issues, so I was mistaken. Sorry about that.
This is caused by liteloader not fastcraft!
Actually, I traced this to K4lib. Liteloader hasn't caused me any trouble so I don't see why you would blame it. Feel free to test a clean forge install and just K4lib if you want to see for yourself. Your comment makes it seem like you dislike Liteloader and want to blame it rather than testing or verifying.
Other than that, I have verified it is NOT FastCraft.