This error crashes the server somethimes or loops 3-4 times.

If this problem hasn't already been reported, please open a ticket
at https://github.com/dmulloy2/ProtocolLib/issues with the following data:
Stack Trace:
java.lang.IllegalArgumentException: Unable to find a field null with the type com.mojang.authlib.GameProfile in net.minecraft.network.protocol.login.PacketLoginInStart
at com.comphenix.protocol.reflect.FuzzyReflection.getFieldByType(FuzzyReflection.java:397)
at com.comphenix.protocol.reflect.accessors.Accessors.getFieldAccessor(Accessors.java:57)
at com.comphenix.protocol.injector.netty.ChannelInjector.handleLogin(ChannelInjector.java:658)
at com.comphenix.protocol.injector.netty.ChannelInjector.decode(ChannelInjector.java:591)
at io.netty.handler.codec.ByteToMessageDecoder.decodeRemovalReentryProtection(ByteToMessageDecoder.java:519)
at io.netty.handler.codec.ByteToMessageDecoder.callDecode(ByteToMessageDecoder.java:458)
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:280)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:336)
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:308)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
at com.comphenix.protocol.injector.netty.ChannelInjector$2.channelRead(ChannelInjector.java:292)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:336)
at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:323)
at io.netty.handler.codec.ByteToMessageDecoder.callDecode(ByteToMessageDecoder.java:444)
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:280)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
at io.netty.handler.timeout.IdleStateHandler.channelRead(IdleStateHandler.java:286)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919)
at io.netty.channel.epoll.AbstractEpollStreamChannel$EpollStreamUnsafe.epollInReady(AbstractEpollStreamChannel.java:800)
at io.netty.channel.epoll.EpollEventLoop.processReady(EpollEventLoop.java:499)
at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:397)
at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:997)
at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
at java.base/java.lang.Thread.run(Thread.java:833)
Dump:
Parameters:
io.netty.buffer.PooledUnsafeDirectByteBuf@1ef195f1[
memoryAddress=139749472849936
recyclerHandle=io.netty.util.Recycler$DefaultHandle@2c8979fc
chunk=Chunk(5c4eed37: 11%, 434176/4194304)
handle=1125929971613696
memory=java.nio.DirectByteBuffer[pos=0 lim=4194304 cap=4194304]
offset=16384
length=3
maxLength=16
cache=io.netty.buffer.PoolThreadCache@4063f4b1
tmpNioBuf=
allocator=PooledByteBufAllocator(directByDefault: true)
refCnt=2
readerIndex=3
writerIndex=3
markedReaderIndex=0
markedWriterIndex=0
maxCapacity=2147483647
]
manager:
com.comphenix.protocol.injector.PacketFilterManager@593fa155[
unhookTask=com.comphenix.protocol.injector.DelayedSingleTask@d20fabf
packetListeners=[PacketAdapter[plugin=LoginSecurity, sending=ListeningWhitelist[priority=LOW, packets=[SET_SLOT[class=ClientboundCustomChatCompletionsPacket, id=22], WINDOW_ITEMS[class=PacketPlayOutWindowItems, id=20], WINDOW_DATA[class=PacketPlayOutWindowData, id=21]], gamephase=PLAYING, options=[]], receiving=EMPTY_WHITELIST], PacketAdapter[plugin=GraveStonesPlus, sending=EMPTY_WHITELIST, receiving=ListeningWhitelist[priority=NORMAL, packets=[UPDATE_SIGN[class=PacketPlayInUpdateSign, id=43]], gamephase=PLAYING, options=[]]]]
packetInjector=com.comphenix.protocol.injector.netty.ProtocolInjector$5@7639be68
playerInjection=com.comphenix.protocol.injector.netty.ProtocolInjector$4@77297c87
inputBufferedPackets=[]
recievedListeners=com.comphenix.protocol.injector.SortedPacketListenerList@53384e3e
sendingListeners=com.comphenix.protocol.injector.SortedPacketListenerList@59c7b3e4
hasClosed=false
classLoader=org.bukkit.plugin.java.PluginClassLoader@5fcc7da9
reporter=com.comphenix.protocol.ProtocolLib$1@62368c4a
server=CraftServer{serverName=CraftBukkit,serverVersion=3721-Spigot-d2fdfe3-19de355,minecraftVersion=1.19.4}
library=ProtocolLib v4.8.0
asyncFilterManager=com.comphenix.protocol.async.AsyncFilterManager@4f1ff597
knowsServerPackets=true
knowsClientPackets=true
phaseLoginCount=0
phasePlayingCount=2
packetCreation=false
nettyInjector=com.comphenix.protocol.injector.netty.ProtocolInjector@2bcdb048
pluginVerifier=com.comphenix.protocol.injector.PluginVerifier@1964910d
hasRecycleDistance=true
minecraftVersion=(MC: 1.19.4)
debug=false
]
Sender:
com.comphenix.protocol.injector.netty.ChannelInjector@34658950[
decodeBuffer=protected void net.minecraft.network.PacketDecoder.decode(io.netty.channel.ChannelHandlerContext,io.netty.buffer.ByteBuf,java.util.List) throws java.lang.Exception
encodeBuffer=protected void net.minecraft.network.PacketEncoder.encode(io.netty.channel.ChannelHandlerContext,java.lang.Object,io.netty.buffer.ByteBuf) throws java.lang.Exception
factory=com.comphenix.protocol.injector.netty.InjectionFactory@7b72cd2d
player=CraftPlayer{name=diviselqni}
updated=
playerName=diviselqni
playerConnection=
networkManager=net.minecraft.network.NetworkManager@5acb7cd3
originalChannel=[id: 0x4946da70, L:/172.18.0.4:25040 - R:/151.237.99.192:51610]
channelField=VolatileField [accessor=DefaultFieldAccessor [field=public io.netty.channel.Channel net.minecraft.network.NetworkManager.m], container=net.minecraft.network.NetworkManager@5acb7cd3, previous=[id: 0x4946da70, L:/172.18.0.4:25040 - R:/151.237.99.192:51610], current=com.comphenix.protocol.injector.netty.ChannelInjector$3@362f0dc3, previousLoaded=true, currentSet=true, forceAccess=true]
packetMarker={}
currentEvent=
finalEvent=
unfilteredProcessedPackets=com.comphenix.protocol.injector.netty.PacketFilterQueue@8616b6e
vanillaDecoder=net.minecraft.network.PacketDecoder@9cdb355
vanillaEncoder=net.minecraft.network.PacketEncoder@6648aec3
finishQueue=[]
channelListener=com.comphenix.protocol.injector.netty.ProtocolInjector@2bcdb048
processor=com.comphenix.protocol.injector.NetworkProcessor@2b7ec2b1
injected=true
closed=false
cumulation=PooledUnsafeDirectByteBuf(ridx: 3, widx: 3, cap: 3)
cumulator=io.netty.handler.codec.ByteToMessageDecoder$1@37ff9fa3
singleDecode=false
first=true
firedChannelRead=false
selfFiredChannelRead=true
decodeState=1
discardAfterReads=16
numReads=0
added=true
]
Version:
ProtocolLib v4.8.0
Java Version:
17.0.6
Server:
3721-Spigot-d2fdfe3-19de355 (MC: 1.19.4)

You need to use the latest Dev-Build: https://ci.dmulloy2.net/job/ProtocolLib/
The version you are using does not support 1.19.4

Yep, I have the same issue with Paper 1.19.4