Game Crash when load a chunk with Touhou Little Maid: Exception ticking world "java.util.ConcurrentModificationException: null"

[YuriMontana]

Context

Describe the bug
The server crashes with a ConcurrentModificationException while ticking the world. The stack trace points to PersistentEntitySectionManager.updateChunkStatus which is triggered by ChunkHolder.demoteFullChunk.

To Reproduce
The crash occurred during normal world/server ticking. A player was logged in at x=-23.50, y=75.88, z=700.50.
No specific action was being taken; it appears related to chunk loading/unloading mechanics.

Crash Report

https://mclo.gs/rsRjG8t