Hello!
The server crashed while a player was flying around in a world generated with the Lost Cities.

Minecraft Version: 1.12.2
Forge Version: 14.23.5.2838
The Lost Cities Version: 2.0.21
McJtyLib Version: 3.5.4

Crash Report: https://gist.github.com/mrAppleXZ/3a2cabf47fd27cf6e45b72d08cddbb43
The Lost Cities configuration files: https://drive.google.com/open?id=1B9PYmwGeDsm-rRDuNfudBfWLbwPeX3m2

The same here: https://pastebin.com/jVcx9Qhv
Minecraft Version: 1.12.2
Forge Version: 14.23.5.2847
The Lost Cities Version: 2.0.21
McJtyLib Version: 3.5.4