I'm on a multiplayer modpack with a friend and we use the Essential mod to play in multiplayer, I don't think it has anything to do with our other mods as they were working perfectly fine but the weapons are making us get an internal exception: Java.lang.IndexOutOfBoundsException
We think it's the weapons, as I got a weapon and tried holding it and was immediately given that exception we tried it in a separate creative world where in single player was working perfectly fine and in multiplayer creative was also working fine but when we went on a survival test world it gave us an exception

This is a bug both in 1.18 and 1.19 which we weren't able to fix. However it doesn't happen in 1.20 so please update your minecraft version.