When watchdog shuts off the server there is possibility of null pointer being thrown preventing shutdown and stuck forever unless killed

[ham1255]

how to reproduce

• make sure prevent-moving-into-unloaded-chunks: false in paper's config
• Launch a pufferfish server
• make ton of players join the server (you can use https://github.com/PureGero/minecraft-stress-test for that) and tell bots to move in 1000x1000 or 2000x2000 radius
• wait for watchdog to shutoff the server (due sync chunk loading)

[20:15:33 INFO]: Bot125 lost connection: Server is restarting
[20:15:33 INFO]: Bot125 left the game
[20:15:33 INFO]: Ham1255 lost connection: Server is restarting
[20:15:33 WARN]: Exception in thread "Paper Watchdog Thread" java.lang.NullPointerException: Cannot invoke "it.unimi.dsi.fastutil.ints.IntArrayList.getInt(int)" because "this.wrapped" is null
[20:15:33 WARN]: 	at it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap$MapIterator.nextEntry(Int2ObjectOpenHashMap.java:657)
[20:15:33 WARN]: 	at it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap$ValueIterator.next(Int2ObjectOpenHashMap.java:1164)
[20:15:33 WARN]: 	at net.minecraft.server.level.PlayerChunkMap.b(PlayerChunkMap.java:1237)
[20:15:33 WARN]: 	at net.minecraft.server.level.ChunkProviderServer.a(ChunkProviderServer.java:949)
[20:15:33 WARN]: 	at net.minecraft.server.level.WorldServer$a.f(WorldServer.java:2626)
[20:15:33 WARN]: 	at net.minecraft.server.level.WorldServer$a.b(WorldServer.java:2514)
[20:15:33 WARN]: 	at io.papermc.paper.chunk.system.entity.EntityLookup.entityStatusChange(EntityLookup.java:279)
[20:15:33 WARN]: 	at io.papermc.paper.chunk.system.entity.EntityLookup$EntityCallback.a(EntityLookup.java:823)
[20:15:33 WARN]: 	at net.minecraft.world.entity.Entity.b(Entity.java:4549)
[20:15:33 WARN]: 	at net.minecraft.world.entity.Entity.a(Entity.java:705)
[20:15:33 WARN]: 	at net.minecraft.world.entity.player.EntityHuman.a(EntityHuman.java:1491)
[20:15:33 WARN]: 	at net.minecraft.server.level.WorldServer.a(WorldServer.java:1578)
[20:15:33 WARN]: 	at net.minecraft.server.players.PlayerList.remove(PlayerList.java:624)
[20:15:33 WARN]: 	at net.minecraft.server.network.PlayerConnection.onDisconnect(PlayerConnection.java:2120)
[20:15:33 WARN]: 	at net.minecraft.server.network.PlayerConnection.disconnect(PlayerConnection.java:521)
[20:15:33 WARN]: 	at net.minecraft.server.network.PlayerConnection.disconnect(PlayerConnection.java:462)
[20:15:33 WARN]: 	at net.minecraft.server.players.PlayerList.removeAll(PlayerList.java:1315)
[20:15:33 WARN]: 	at net.minecraft.server.MinecraftServer.t(MinecraftServer.java:958)
[20:15:33 WARN]: 	at net.minecraft.server.dedicated.DedicatedServer.t(DedicatedServer.java:800)
[20:15:33 WARN]: 	at net.minecraft.server.MinecraftServer.close(MinecraftServer.java:901)
[20:15:33 WARN]: 	at org.spigotmc.WatchdogThread.run(WatchdogThread.java:233)

• video showing the whole process https://youtu.be/qdWccufOHp4
• logs: https://mclo.gs/jybU5CC

Server details

> plugins
[20:43:51 INFO]: Plugins (0): 
> version
[20:43:56 INFO]: Checking version, please wait...
[20:43:58 INFO]: This server is running Pufferfish version git-Pufferfish-58 (MC: 1.19.3) (Implementing API version 1.19.3-R0.1-SNAPSHOT) (Git: 9edb00b on HEAD)
You are on the latest version!
Previous version: git-Purpur-1915 (MC: 1.19.3)
> datapack list
[20:44:04 INFO]: There are 2 data packs enabled: [vanilla (built-in)], [file/bukkit (world)]
[20:44:04 INFO]: There are no more data packs available

more info

• This issue does not happen on PaperMC