At random intervals while playing the server crashes. Me and my friend have narrowed it down to what we think is burning a metal while loading chunks. We are also using two other mods: JourneyMap and VeinMiner.

Minecraft Version: 1.11.2
Forge Version:13.20.0.2214

Crash Report:
http://pastebin.com/Zfj03smF

I think I located the issue. Did either of you happen to run out of metals right when it crashed?

I've been drinking a pewter vial everytime the server goes down, because it wipes any metals you've stored, so I'd have to say probably. I'll try and see if that's the problem.

Okay, after testing it a few times my answer is Yes it does crash when you run out of metal. Also to correct an error, it seemed like the server wiped my metal storage because I ran out metal during the time of the crash. In turn I drank another vial thinking it was the server and not me actually running out. Sorry for the confusion.

Thanks! You make great mods!