As a way to practice modding I'm trying to add signs to my 1.19.2 mod, but when placing the sign and opening the sign edit screen it crashes with this log: https://mclo.gs/hxLFTGn
 
	 
 
	I can't find any info on the crash so i don't know what to do anymore.
 
package com.an12854.leanmod.block.entity;
import com.an12854.leanmod.Leanmod;
import com.an12854.leanmod.block.ModBlocks;
import net.minecraft.world.level.block.entity.BlockEntityType;
import net.minecraftforge.eventbus.api.IEventBus;
import net.minecraftforge.registries.DeferredRegister;
import net.minecraftforge.registries.ForgeRegistries;
import net.minecraftforge.registries.RegistryObject;
public class ModBlockEntities {
    public static final DeferredRegister<BlockEntityType<?>> BLOCK_ENTITIES =
            DeferredRegister.create(ForgeRegistries.BLOCK_ENTITY_TYPES, Leanmod.MODID);
    public static final RegistryObject<BlockEntityType<ModSignBlockEntity>> SIGN_BLOCK_ENTITIES =
            BLOCK_ENTITIES.register("sign_block_entity", () ->
                    BlockEntityType.Builder.of(ModSignBlockEntity::new,
                            ModBlocks.LEAN_WALL_SIGN.get(),
                            ModBlocks.LEAN_SIGN.get()).build(null));
    public static void register(IEventBus eventBus) {
        BLOCK_ENTITIES.register(eventBus);
    }
}
	Here is the custom BlockEntities