• This issue is not solved in a development build

Describe the bug
PaperSpigot 1.8.8 Java version 17, the server just crash after someone join, It happens sometimes, not always.

To Reproduce
Steps to reproduce the behavior:
I don't know, someone join on the server and happens the crash

Version Info
v5.2.0

Additional context

[17:11:15] [Server thread/INFO]: Voxxel[/XXXXXX:37453] logged in with entity id 52403423 at ([world]0.5, 51.0, 0.5)
[17:11:15] [Server thread/WARN]: Entity threw exception at world:0.5,51.0,0.5
[17:11:15] [Server thread/WARN]: net.minecraft.server.v1_8_R3.ReportedException: Sending packet
[17:11:15] [Server thread/WARN]: at net.minecraft.server.v1_8_R3.PlayerConnection.sendPacket(PlayerConnection.java:925)
[17:11:15] [Server thread/WARN]: at net.minecraft.server.v1_8_R3.EntityTrackerEntry.updatePlayer(EntityTrackerEntry.java:356)
[17:11:15] [Server thread/WARN]: at net.minecraft.server.v1_8_R3.EntityTracker.a(EntityTracker.java:249)
[17:11:15] [Server thread/WARN]: at net.minecraft.server.v1_8_R3.EntityPlayer.t_(EntityPlayer.java:270)
[17:11:15] [Server thread/WARN]: at net.minecraft.server.v1_8_R3.World.entityJoinedWorld(World.java:1650)
[17:11:15] [Server thread/WARN]: at net.minecraft.server.v1_8_R3.World.g(World.java:1617)
[17:11:15] [Server thread/WARN]: at net.minecraft.server.v1_8_R3.World.tickEntities(World.java:1450)
[17:11:15] [Server thread/WARN]: at net.minecraft.server.v1_8_R3.WorldServer.tickEntities(WorldServer.java:600)
[17:11:15] [Server thread/WARN]: at net.minecraft.server.v1_8_R3.MinecraftServer.B(MinecraftServer.java:846)
[17:11:15] [Server thread/WARN]: at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:378)
[17:11:15] [Server thread/WARN]: at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:713)
[17:11:15] [Server thread/WARN]: at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:616)
[17:11:15] [Server thread/WARN]: at java.base/java.lang.Thread.run(Thread.java:842)
[17:11:15] [Server thread/WARN]: Caused by: java.lang.NullPointerException: type cannot be null
[17:11:15] [Server thread/WARN]: at com.google.common.base.Preconditions.checkNotNull(Preconditions.java:229)
[17:11:15] [Server thread/WARN]: at com.comphenix.protocol.injector.StructureCache.getStructure(StructureCache.java:138)
[17:11:15] [Server thread/WARN]: at com.comphenix.protocol.events.PacketContainer.(PacketContainer.java:126)
[17:11:15] [Server thread/WARN]: at com.comphenix.protocol.injector.netty.manager.NetworkManagerInjector.onPacketSending(NetworkManagerInjector.java:96)
[17:11:15] [Server thread/WARN]: at com.comphenix.protocol.injector.netty.channel.NettyChannelInjector.processOutbound(NettyChannelInjector.java:553)
[17:11:15] [Server thread/WARN]: at com.comphenix.protocol.injector.netty.channel.NettyChannelInjector$2.doProxyRunnable(NettyChannelInjector.java:456)
[17:11:15] [Server thread/WARN]: at com.comphenix.protocol.injector.netty.channel.NettyEventLoopProxy.proxyRunnable(NettyEventLoopProxy.java:43)
[17:11:15] [Server thread/WARN]: at com.comphenix.protocol.injector.netty.channel.NettyEventLoopProxy.execute(NettyEventLoopProxy.java:252)
[17:11:15] [Server thread/WARN]: at net.minecraft.server.v1_8_R3.NetworkManager.a(NetworkManager.java:192)
[17:11:15] [Server thread/WARN]: at net.minecraft.server.v1_8_R3.NetworkManager.handle(NetworkManager.java:141)
[17:11:15] [Server thread/WARN]: at net.minecraft.server.v1_8_R3.PlayerConnection.sendPacket(PlayerConnection.java:911)
[17:11:15] [Server thread/WARN]: ... 12 more
[17:11:15] [Server thread/ERROR]: Encountered an unexpected exception
net.minecraft.server.v1_8_R3.ReportedException: Sending packet
at net.minecraft.server.v1_8_R3.PlayerConnection.sendPacket(PlayerConnection.java:925) ~[patched_1.8.8.jar:git-PaperSpigot-445]
at net.minecraft.server.v1_8_R3.EntityTrackerEntry.broadcastIncludingSelf(EntityTrackerEntry.java:312) ~[patched_1.8.8.jar:git-PaperSpigot-445]
at net.minecraft.server.v1_8_R3.EntityTrackerEntry.b(EntityTrackerEntry.java:277) ~[patched_1.8.8.jar:git-PaperSpigot-445]
at net.minecraft.server.v1_8_R3.EntityTrackerEntry.track(EntityTrackerEntry.java:203) ~[patched_1.8.8.jar:git-PaperSpigot-445]
at net.minecraft.server.v1_8_R3.EntityTracker.updatePlayers(EntityTracker.java:177) ~[patched_1.8.8.jar:git-PaperSpigot-445]
at net.minecraft.server.v1_8_R3.MinecraftServer.B(MinecraftServer.java:863) ~[patched_1.8.8.jar:git-PaperSpigot-445]
at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:378) ~[patched_1.8.8.jar:git-PaperSpigot-445]
at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:713) ~[patched_1.8.8.jar:git-PaperSpigot-445]
at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:616) [patched_1.8.8.jar:git-PaperSpigot-445]
at java.lang.Thread.run(Thread.java:842) [?:?]
Caused by: java.lang.NullPointerException: type cannot be null
at com.google.common.base.Preconditions.checkNotNull(Preconditions.java:229) ~[patched_1.8.8.jar:git-PaperSpigot-445]
at com.comphenix.protocol.injector.StructureCache.getStructure(StructureCache.java:138) ~[?:?]
at com.comphenix.protocol.events.PacketContainer.(PacketContainer.java:126) ~[?:?]
at com.comphenix.protocol.injector.netty.manager.NetworkManagerInjector.onPacketSending(NetworkManagerInjector.java:96) ~[?:?]
at com.comphenix.protocol.injector.netty.channel.NettyChannelInjector.processOutbound(NettyChannelInjector.java:553) ~[?:?]
at com.comphenix.protocol.injector.netty.channel.NettyChannelInjector$2.doProxyRunnable(NettyChannelInjector.java:456) ~[?:?]
at com.comphenix.protocol.injector.netty.channel.NettyEventLoopProxy.proxyRunnable(NettyEventLoopProxy.java:43) ~[?:?]
at com.comphenix.protocol.injector.netty.channel.NettyEventLoopProxy.execute(NettyEventLoopProxy.java:252) ~[?:?]
at net.minecraft.server.v1_8_R3.NetworkManager.a(NetworkManager.java:192) ~[patched_1.8.8.jar:git-PaperSpigot-445]
at net.minecraft.server.v1_8_R3.NetworkManager.handle(NetworkManager.java:141) ~[patched_1.8.8.jar:git-PaperSpigot-445]
at net.minecraft.server.v1_8_R3.PlayerConnection.sendPacket(PlayerConnection.java:911) ~[patched_1.8.8.jar:git-PaperSpigot-445]
... 9 more
[17:11:15] [Server thread/ERROR]: Cause of unexpected exception was
java.lang.NullPointerException: type cannot be null
at com.google.common.base.Preconditions.checkNotNull(Preconditions.java:229) ~[patched_1.8.8.jar:git-PaperSpigot-445]
at com.comphenix.protocol.injector.StructureCache.getStructure(StructureCache.java:138) ~[?:?]
at com.comphenix.protocol.events.PacketContainer.(PacketContainer.java:126) ~[?:?]
at com.comphenix.protocol.injector.netty.manager.NetworkManagerInjector.onPacketSending(NetworkManagerInjector.java:96) ~[?:?]
at com.comphenix.protocol.injector.netty.channel.NettyChannelInjector.processOutbound(NettyChannelInjector.java:553) ~[?:?]
at com.comphenix.protocol.injector.netty.channel.NettyChannelInjector$2.doProxyRunnable(NettyChannelInjector.java:456) ~[?:?]
at com.comphenix.protocol.injector.netty.channel.NettyEventLoopProxy.proxyRunnable(NettyEventLoopProxy.java:43) ~[?:?]
at com.comphenix.protocol.injector.netty.channel.NettyEventLoopProxy.execute(NettyEventLoopProxy.java:252) ~[?:?]
at net.minecraft.server.v1_8_R3.NetworkManager.a(NetworkManager.java:192) ~[patched_1.8.8.jar:git-PaperSpigot-445]
at net.minecraft.server.v1_8_R3.NetworkManager.handle(NetworkManager.java:141) ~[patched_1.8.8.jar:git-PaperSpigot-445]
at net.minecraft.server.v1_8_R3.PlayerConnection.sendPacket(PlayerConnection.java:911) ~[patched_1.8.8.jar:git-PaperSpigot-445]
at net.minecraft.server.v1_8_R3.EntityTrackerEntry.broadcastIncludingSelf(EntityTrackerEntry.java:312) ~[patched_1.8.8.jar:git-PaperSpigot-445]
at net.minecraft.server.v1_8_R3.EntityTrackerEntry.b(EntityTrackerEntry.java:277) ~[patched_1.8.8.jar:git-PaperSpigot-445]
at net.minecraft.server.v1_8_R3.EntityTrackerEntry.track(EntityTrackerEntry.java:203) ~[patched_1.8.8.jar:git-PaperSpigot-445]
at net.minecraft.server.v1_8_R3.EntityTracker.updatePlayers(EntityTracker.java:177) ~[patched_1.8.8.jar:git-PaperSpigot-445]
at net.minecraft.server.v1_8_R3.MinecraftServer.B(MinecraftServer.java:863) ~[patched_1.8.8.jar:git-PaperSpigot-445]
at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:378) ~[patched_1.8.8.jar:git-PaperSpigot-445]
at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:713) ~[patched_1.8.8.jar:git-PaperSpigot-445]
at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:616) [patched_1.8.8.jar:git-PaperSpigot-445]
at java.lang.Thread.run(Thread.java:842) [?:?]

Might be fixed by the latest dev build but could also throw a new error since 1.8 isn't as much tested as newer version of the game.
https://ci.dmulloy2.net/job/ProtocolLib/