Version of Ars Nouveau: 5.8.1
Version of Woodwalkers (used for ReMorphed mod): 5.6
Version of ReMorphed: 4.2

Version of Minecraft: 1.21.1
Version of NeoForge: 21.1.146

Issue:
When rendering the player hand in game, Ars Nouveau has a mixin and Woodwalkers does too.
These seem to have some sort of conflict (potentially) according to the crash log, but not all the time.

Specifically, in the ReMorphed menu, choose Vex (Summoned) then don't hold anything in your hand. The game will crash and the world will be unable to open again, and will just crash continuously. This doesn't seem to happen with a normal Vex morph.

Other mods had no conflicts with Ars hand rendering.

The crash log below shows all the mods installed and the 2 suspected conflicting ones, and the specific crash (player names removed):
Crash Log: https://pastebin.com/cH6EW2j0

have you reported this to woodwalkers? Ars simply uses the vanilla vex rendering, it looks like that mod is not safely guarding against other mods extending vanilla entities.

@baileyholl I have reported the issue to them. I did not know that Ars extended vanilla entities so now I'm sure it's a woodwalkers only issue. Woodwalkers issue link: ToCraft/woodwalkers-mod#176