Crashes after 1.19.3 Paper version update

[LoyalPineapple]

Stack trace

java.lang.NullPointerException: Cannot invoke "it.unimi.dsi.fastutil.ints.IntArrayList.getInt(int)" because "this.wrapped" is null
at it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap$MapIterator.nextEntry(Int2ObjectOpenHashMap.java:657)
at it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap$ValueIterator.next(Int2ObjectOpenHashMap.java:1164)
at net.minecraft.server.level.ChunkTracker.processTrackQueue(ChunkTracker.java:1266)
at net.minecraft.server.level.ChunkTracker.tick(ChunkTracker.java:1278)
at net.minecraft.server.level.ServerChunkCache.tickChunks(ServerChunkCache.java:818)
at net.minecraft.server.level.ServerChunkCache.tick(ServerChunkCache.java:649)
at net.minecraft.server.level.ServerLevel.tick(ServerLevel.java:686)
at net.minecraft.server.MinecraftServer.tickChildren(MinecraftServer.java:1535)
at net.minecraft.server.dedicated.DedicatedServer.tickChildren(DedicatedServer.java:440)
at net.minecraft.server.MinecraftServer.tickServer(MinecraftServer.java:1397)
at net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1173)
at net.minecraft.server.MinecraftServer.lambda$spin$0(MinecraftServer.java:316)
at java.base/java.lang.Thread.run(Thread.java:833)

A detailed walkthrough of the error, its code path and all known details is as follows:

-- Head --
Thread: Server thread
Stacktrace:
at it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap$MapIterator.nextEntry(Int2ObjectOpenHashMap.java:657)
at it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap$ValueIterator.next(Int2ObjectOpenHashMap.java:1164)
at net.minecraft.server.level.ChunkMap.processTrackQueue(ChunkMap.java:1266)
at net.minecraft.server.level.ChunkMap.tick(ChunkMap.java:1278)
at net.minecraft.server.level.ServerChunkCache.tickChunks(ServerChunkCache.java:818)
at net.minecraft.server.level.ServerChunkCache.tick(ServerChunkCache.java:649)
at net.minecraft.server.level.ServerLevel.tick(ServerLevel.java:686)

Plugin and Datapack List

Custom

Actions to reproduce (if known)

No response

Paper version

381

Other

If the issue is not within Paper but is in a plugin, how would you pinpoint which part of a plugin is causing it?

[Warriorrrr]

Not a paper issue, a plugin most likely altered the map from another thread. I say most likely there since you skipped listing what plugins you're running.

[lynxplay]

Closing this as a general duplicate of #6758 or other related issues.
All other instances have been related to plugins accessing internals off the main thread as Warriorrrr pointed out.
Make sure to keep your plugins up to date or try to troubleshoot which plugin is causing this following https://docs.papermc.io/paper/basic-troubleshooting#find-out-what-plugin-is-causing-the-problem.

Feel free to join our discord if you have any further questions.