It doesnt crash during actual gameplay (even when using "Open to LAN" server - it doesnt crash for any of players). But it often crashes when in replay getting to a moment when I morphed (or when opened morph gui?). It will always crash for same replay. But, it always worked fine if I open world where I was already morphed (viewing replay of that).
crash-2018-10-10_19.16.09-client.txt
https://minecraft.curseforge.com/projects/morph