Describe the bug
Sometimes when my server performs an automatic restart (overnight at around 4 am European Summer Time), it will silently deadlock with a ConcurrentModificationException. Notably the process still appears to be running, but server startup does not continue.

This issue has occured in the last two automatic restarts today, and on the 20th, but I have already had this issue in mid summer with much greater frequency.

In the past removing C2ME has stopped the deadlock from occuring.

To Reproduce
I have so far been unable to reproduce this bug in a test environment. Currently, my server starts just as it should, but in the past I have been able to achieve deadlock on a manual restart.

Steps to reproduce:

1. Have a server
2. Install the latest version of C2ME
3. ???

Expected behavior
Uhhh, no deadlock.

Screenshots
N/A

Runtime info (please complete the following information):

• OS: UnRAID OS 6.12.13 w/ Docker 24.0.9, build 2936816
• Minecraft version: 1.21
• Mod version: c2me-fabric-mc1.21-0.2.0+alpha.11.109.jar
• Mod branch: (fill this if you are not using the default ver branches)

Crash reports / logs
https://pastebin.com/qpANpfEw

I have also run this traceback through StackDeobfuscator with Yarn mappings: https://pastebin.com/kqnkf1wn

Other mods
https://pastebin.com/VmEDqrPn

Checklist

• I am using the official version of the mod.
• I tried the latest development version but the issue persists.
• I searched for similar open issues and could not find an existing bug report on this.

Additional context
I am hesitant to use the development version for fear of world corruption

Try reproduce with the 1.21.1 versions of C2ME. It runs on 1.21.

Have installed the 1.21 version, results pending the next overnight restart

So far the issue has not reoccurred. However I have seen similar behaviour after updating before so I'm not really sold that the issue is fixed.

That being said I will close the issue for now