Version

lithium-neoforge-0.14.4+mc1.21.4.

Reproduction Steps

Install Lithium by putting it into the mods folder.
Game Crashes.

Crash Report File

https://paste.ee/p/fpYSt

Notes

I don't know how to read crash reports but this stood out to me, I don't know if it means anything.
Caused by: org.spongepowered.asm.mixin.injection.throwables.InjectionError: LVT in net/minecraft/world/level/block/entity/HopperBlockEntity::ejectItems(Lnet/minecraft/world/level/Level;Lnet/minecraft/core/BlockPos;Lnet/minecraft/world/level/block/entity/HopperBlockEntity;)Z has incompatible changes at opcode 41 in callback lithium.mixins.json:block.hopper.HopperBlockEntityMixin from mod lithium->@Inject::lithiumInsert(Lnet/minecraft/world/level/Level;Lnet/minecraft/core/BlockPos;Lnet/minecraft/world/level/block/entity/HopperBlockEntity;Lorg/spongepowered/asm/mixin/injection/callback/CallbackInfoReturnable;Lnet/minecraft/world/Container;Lnet/minecraft/core/Direction;)V.

Edit: For anyone reading this before a fix is implemented, downgrade NeoForge to an older 1.21.4 version.

Fixed by 55742f4

When will the new version with this fix be released out of curiosity?

as discussed on discord, probably broken by neoforged/NeoForge@3de035b

Fixed by 55742f4