In this line the attack damage of a livingentity seems to be determined, however if a livingentity doesn't have attack damage, but can still do damage, such as a pufferfish it will cause a crash.
https://github.com/DragonsPlusMinecraft/visuality-forge/blob/056b890e42b59b95ef7ba594d0b84aad5e846751/src/main/java/plus/dragons/visuality/config/EntityHitParticleConfig.java#L93