strangely works fine on modded single player. but when playing on a server there is an instant client side crash when trying to use cgm ammo. This popped up on console, not sure if its helpful! UUID of added entity already exists: FallingBlockEntity['Falling Block'/9114, l='ServerLevel[The Outcasts - Metropolis 2]', x=678.50, y=81.00, z=-90.50]

java.lang.NullPointerException: Cannot invoke "net.minecraft.server.MinecraftServer.m_6846_()" because the return value of "net.minecraftforge.network.PacketDistributor.getServer()" is null

Hi, I realised this is in fact the actual error. Seems to be a synchronisation issue in rendering between the server and client? (Been learning a bit about this trying to fix it. Not sure if its helpful!)

Are you able to show the entire log?

sure thing!
Crash Report.pdf