UnsupportedOperationException: Calling Entity#remove on players produces undefined (bad) behavior

Summary

Describe the bug encountered in detail.

Current behavior

I just encountered this stack trace in my log. What can I do to prevent this error from occouring?

Server log file

Startup log: https://pastebin.com/5vE4YcCG Player connect log: https://pastebin.com/QkxVtQzN

Debug log snippet

https://pastebin.com/fuNX2trb

Proposed fixes

Don't call .remove() on Player object.