Okay so an update. I tried putting in -nographics. Still crashes with that error. It seems to crash more often when more people are online. Also I just caught it crashing without a server save, so they may not be related.

May I ask if you were able to solve the problem somehow?
We have the same problem, isolated crashes when the entities go over 100k and a server that crashes every day, always with this error mentioned.

I started taking plugins out one by one that could potentially cause the problem. I started with Convoy, still crashed. Next I took out DynamicPVP, still crashed. Lastly I made it to where nightmares from Raidable Bases didn't spawn, and so far that has worked. Hasn't crashed in about 2 days. Still going through testing though so I'm not sure if it's completely fixed.