[12:31:02 ERROR]: Couldn't place player in world
net.minecraft.ReportedException: Sending packet
at net.minecraft.server.network.ServerGamePacketListenerImpl.send(ServerGamePacketListenerImpl.java:2131) ~[?:?]
at net.minecraft.server.network.ServerGamePacketListenerImpl.send(ServerGamePacketListenerImpl.java:2109) ~[?:?]
at net.minecraft.server.players.PlayerList.placeNewPlayer(PlayerList.java:280) ~[purpur-1.18.2.jar:git-Purpur-1632]
at net.minecraft.server.network.ServerLoginPacketListenerImpl.placeNewPlayer(ServerLoginPacketListenerImpl.java:215) ~[?:?]
at net.minecraft.server.network.ServerLoginPacketListenerImpl.handleAcceptedLogin(ServerLoginPacketListenerImpl.java:196) ~[?:?]
at net.minecraft.server.network.ServerLoginPacketListenerImpl.tick(ServerLoginPacketListenerImpl.java:84) ~[?:?]
at net.minecraft.network.Connection.tick(Connection.java:567) ~[?:?]
at net.minecraft.server.network.ServerConnectionListener.tick(ServerConnectionListener.java:231) ~[?:?]
at net.minecraft.server.MinecraftServer.tickChildren(MinecraftServer.java:1651) ~[purpur-1.18.2.jar:git-Purpur-1632]
at net.minecraft.server.dedicated.DedicatedServer.tickChildren(DedicatedServer.java:522) ~[purpur-1.18.2.jar:git-Purpur-1632]
at net.minecraft.server.MinecraftServer.tickServer(MinecraftServer.java:1483) ~[purpur-1.18.2.jar:git-Purpur-1632]
at net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1247) ~[purpur-1.18.2.jar:git-Purpur-1632]
at net.minecraft.server.MinecraftServer.lambda$spin$1(MinecraftServer.java:321) ~[purpur-1.18.2.jar:git-Purpur-1632]
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:907) ~[guava-31.0.1-jre.jar:?]
at com.comphenix.protocol.injector.StructureCache.getStructure(StructureCache.java:138) ~[ProtocolLib.jar:?]
at com.comphenix.protocol.events.PacketContainer.(PacketContainer.java:126) ~[ProtocolLib.jar:?]
at com.comphenix.protocol.injector.netty.manager.NetworkManagerInjector.onPacketSending(NetworkManagerInjector.java:96) ~[ProtocolLib.jar:?]
at com.comphenix.protocol.injector.netty.channel.NettyChannelInjector.processOutbound(NettyChannelInjector.java:553) ~[ProtocolLib.jar:?]
at com.comphenix.protocol.injector.netty.channel.NettyChannelInjector$2.doProxyRunnable(NettyChannelInjector.java:456) ~[ProtocolLib.jar:?]
at com.comphenix.protocol.injector.netty.channel.NettyEventLoopProxy.proxyRunnable(NettyEventLoopProxy.java:43) ~[ProtocolLib.jar:?]
at com.comphenix.protocol.injector.netty.channel.NettyEventLoopProxy.execute(NettyEventLoopProxy.java:252) ~[ProtocolLib.jar:?]
at net.minecraft.network.Connection.writePacket(Connection.java:435) ~[?:?]
at net.minecraft.network.Connection.send(Connection.java:382) ~[?:?]
at net.minecraft.server.network.ServerGamePacketListenerImpl.send(ServerGamePacketListenerImpl.java:2123) ~[?:?]
... 13 more

Please provide:

• precise build version of ProtocolLib
• precise build version of your server software (ex: Paper 1.21.1-35-master@be1078f)
• the list of the plugins installed on your server

Should be fixed in the latest dev build so please use the latest dev build and try again: https://ci.dmulloy2.net/job/ProtocolLib/lastSuccessfulBuild/