this is a mod on CureseForge called Vault Hunter i tried to run it white use system memory setting on but crashed with this log https://pastebin.com/YCbbBh1V
and i tried it with 8192 MB memory and it crashed with this log https://pastebin.com/Ezeib7mW
No, this should be a client-only event handler, because registerParticleFactory is a client only thing. However your registry stuff for ParticleType needs to be a in a common class.
It needs to be in a common class. With your current code, your mod will crash servers, because you are loading client-only classes on the server.