ViaVersion java.lang.NullPointerException: Packet handling error

`/viaversion dump` Output

https://dump.viaversion.com/8a4660637b79542d105816176739a909b9f5ae79f57185b0dc00451b9ec72906

Console Error

None, just Minecraft error;

---- Minecraft Network Protocol Error Report ----
// Maybe this time it will work!

Time: 2024-07-31 15:27:26
Description: Packet handling error

java.lang.NullPointerException: Packet handling error


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

-- Head --
Thread: Render thread
Stacktrace:
	at zj.a(SourceFile:56)

-- Incoming Packet --
Details:
	Type: clientbound/minecraft:add_entity
	Is Terminal: false
	Is Skippable: false
Stacktrace:
	at zj.a(SourceFile:56)
	at fzc.a(SourceFile:136)
	at fzc.a(SourceFile:113)
	at zj.a(SourceFile:32)
	at bph.d(SourceFile:162)
	at bpl.d(SourceFile:23)
	at bph.B(SourceFile:136)
	at bph.bB(SourceFile:121)
	at fgo.c(SourceFile:1240)
	at fgo.f(SourceFile:882)
	at net.minecraft.client.main.Main.main(SourceFile:256)

-- Connection --
Details:
	Protocol: play
	Flow: CLIENTBOUND
	Server type: OTHER
	Server brand: ~~NULL~~

-- System Details --
Details:
	Minecraft Version: 1.21
	Minecraft Version ID: 1.21
	Operating System: Windows 10 (amd64) version 10.0
	Java Version: 21.0.3, Microsoft
	Java VM Version: OpenJDK 64-Bit Server VM (mixed mode), Microsoft
	Memory: 710834800 bytes (677 MiB) / 1241513984 bytes (1184 MiB) up to 2147483648 bytes (2048 MiB)
	CPUs: 8
	Processor Vendor: GenuineIntel
	Processor Name: Intel(R) Core(TM) i7-7700K CPU @ 4.20GHz
	Identifier: Intel64 Family 6 Model 158 Stepping 9
	Microarchitecture: Kaby Lake
	Frequency (GHz): 4.20
	Number of physical packages: 1
	Number of physical CPUs: 4
	Number of logical CPUs: 8
	Graphics card #0 name: NVIDIA GeForce GTX 1070
	Graphics card #0 vendor: NVIDIA
	Graphics card #0 VRAM (MiB): 8192.00
	Graphics card #0 deviceId: VideoController1
	Graphics card #0 versionInfo: 31.0.15.3623
	Memory slot #0 capacity (MiB): 8192.00
	Memory slot #0 clockSpeed (GHz): 2.40
	Memory slot #0 type: DDR4
	Memory slot #1 capacity (MiB): 8192.00
	Memory slot #1 clockSpeed (GHz): 2.40
	Memory slot #1 type: DDR4
	Virtual memory max (MiB): 30705.08
	Virtual memory used (MiB): 26615.53
	Swap memory total (MiB): 14354.28
	Swap memory used (MiB): 1526.92
	Space in storage for jna.tmpdir (MiB): available: 11124.24, total: 228268.34
	Space in storage for org.lwjgl.system.SharedLibraryExtractPath (MiB): available: 11124.24, total: 228268.34
	Space in storage for io.netty.native.workdir (MiB): available: 11124.24, total: 228268.34
	Space in storage for java.io.tmpdir (MiB): available: 11124.24, total: 228268.34
	Space in storage for workdir (MiB): available: 11124.24, total: 228268.34
	JVM Flags: 9 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xss1M -Xmx2G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M

Bug Description

Joining 1.8 server with 1.21 client sometimes produces this error.

Steps to Reproduce

Create 1.8 server
Join with 1.21 client

Expected Behavior

Obvious

Additional Server Info

No response

Checklist

[X] Via plugins are only running on EITHER the backend servers (e.g. Paper) OR the proxy (e.g. Velocity), not on both.
[X] I have included a ViaVersion dump.
[X] If applicable, I have included a paste (not a screenshot) of the error.
[X] I have tried the latest build(s) from https://ci.viaversion.com/ and the issue still persists.