Lithium breaks a NeoForge patch preventing a loading deadlock caused by `ServerChunkCache::getChunk`

[Fuzss]

Minecraft: 1.21.8
NeoForge: 21.8.4-beta
Lithium: 0.18.0+mc1.21.8

latest.log

The Neo patch and the reasons for it is outlined here:
MinecraftForge/MinecraftForge#7697
neoforged/NeoForge#99
neoforged/NeoForge#110

To reproduce I have a mod that allows mobs (like illagers and drowneds) to spawn with equipment, which is applied during EntityJoinLevelEvent.

Without Lithium this works fine, with Lithium installed it is very easy to get a deadlock.

Steps for reproducing:

• Install the following mods: Lithium, Puzzles Lib, Armored Foes
• Create a world using the following seed: -6902519934141284895
• Run this command: /tp @s -880 ~ -1568
• Fly out in the ocean a bit, you will notice chunks stop generating and upon trying to leave the world via the pause screen Saving world will show forever. The log does not give any hint at this.

The problem is this Mixin: https://github.com/CaffeineMC/lithium/blob/develop/common/src/main/java/net/caffeinemc/mods/lithium/mixin/world/chunk_access/ServerChunkCacheMixin.java

Also on another note I've added the patch to Fabric, but due to your Mixin it is broken (this is the same implementation used in Armor Foes, the source of which is not public yet).
So far my only option is to set mixin.world.chunk_access=false which is of course not ideal.

Honestly this is such a serious and hard to debug issue that it would be great in addition to fixing the Neo patch to also implement it on Fabric in Lithium itself.

[Fuzss]

Also see one of the unofficial Lithium NeoForge ports which preserves the patch applied correctly: Reforged-Hub#7

[TsXor]

I encountered this bug on Radium Reforged (Forge port of Lithium) today.
By checking call stack in Spark profile, I found this bug is triggered by the force chunk loading function of FTB Chunks.
Inside loggedIn method, FTB Chunks will try to load chunk tickets when the first one in a team logged in, and calls ForgeChunkManager.forceChunk, which eventually calls injected ServerChunkCache::getChunk mentioned above.
Thus, the priority of this issue may be raised, as FTB Chunks is a quite widely-used mod.

Notes: The symptoms of my server is that it will crash due to an ultra long tick that exceeds tick time limit after the first player joins. Due to such a symptom, the Spark profile was a little hard to collect, which needs to start profiler and use spark profiler stop --save-to-file to finish profiling right after the first player joins.

EDIT: I tried to review code of Radium Reforged, and found it already contains patch in neoforged/NeoForge#110, however, neoforged/NeoForge#99 is missing. This reply is off topic.

YET ANOTHER EDIT: I found ModernFix contains neoforged/NeoForge#99 for Forge, however the implementation might be problematic, as it tries to retrieve holder from a map.