Server Crash Reports:
http://paste.ubuntu.com/p/kZyYdHvFfd/
http://paste.ubuntu.com/p/VdTdv8rft9/

@BlackJar72 Mod is calling for something that does not exist on the server-end, might want to check proxy classes. I'll start working on code + new textures for this mod when I can unfuck my sleep at this point.

I've been gone a few days to visit my sister. I'll try to look at this when I can.

It looks like the function in questions is armorItemInSlot() -- which is weird, but maybe only used for rendering armor (in vanilla)? I have one idea I can try, if that doesn't work I'm not sure what to do.

Note that I don't have a server so it gets very little server testing before being released into the wild.

I've not compiled it yet, in case any other changes might be made, though, well, probably not right now -- at least, not by me.

In Eclipse there is a launch server option, if your using IDEA there should be a similar option. That particular server is the same as when a dedicated server runs.

I never noticed the launch server option -- I'll look into that (though it would still require a client to test).

I only know of one other way to do what it was doing -- I'll probably release the bug fix tomorrow. I probably won't be adding the other enhancement I was thinking of because put simply if I do much modding it will probably Climatic Biomes rather than Dungeon Mobs.

I've pushed forth Blackjar's bugfix. Let me know if it works @kreezxil

Fixed.