Servers deadlock on launch

[Fisch37]

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

• [x] I am using the official version of the mod.
• [ ] I tried the latest development version but the issue persists.
• [x] 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

[ishland]

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

[Fisch37]

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