So last night, me and a friend were playing on our server, building a base with Create parts in it. Reportedly, my friend placed down a copper valve handle, and both of our games instantly crashed. Keep in mind, we had been using create parts all over this map, and nothing presented a problem, until now. Now the island where this base is, is completely inaccessible, because the second the chunk loads in, the game crashes. I don't want to remove create from the server, because it would be a pain to set everything up again, and it's kind of useful for what we want to do. I'll attach the crash log from my game to this issue report, so please tell me if something else is crashing my game. I just thought it might be Create since it's the last block placed that caused the problem.
first crash (server).txt
testing crash (singleplayer).txt

From the crash log, the issue seems to be caused by a mixin in Immersive Engineering, AbstractBlockStateMixin, possibly running within a contraption world? I'm not sure how to test it properly at the moment though

Yeah, according to a friend, it seems like an Immersive Engineering pipe was placed on a Create block, and then rotated it with a create machine, and it instantly crashed both of us. They were able to replicate it in a singleplayer world. So, for the time being, don't put IE pipes on rotating Create objects.

I believe this is the same issue as #2150, so I will close it as a duplicate