This bug is reproducible but requires a very precise timing to pull off. I have a script that sends restart countdown servermsgs, including sending one final "Restarting NOW!" message right before sysytemd service is stopped. During last game session, server failed to shut down cleanly and persist server state, partially wiping player progress. After looking at the logs and some lucky guessing I was able to pinpoint the issue to that one final servermsg. Here's how to reproduce this:
1. Create a script that sleeps for a few seconds, sends servermsg and immediately terminates the server.
2. Log into the game.
3. Execute the script.
4. Quit the game immediately before servermsg.
5. My guess is that servermsg is either racing with shutdown, or attempts to message a disconnected player that did not yet have time to fully close the client session.
hs_err_pid15877.log systemd.log