Replace `Option<ItemStack>` with `ItemStack`

[rj00a]

Describe the problem related to your feature request.

In Valence we are using Option to indicate the emptyness of an itemstack. However, vanilla does something semantically different.

public boolean isEmpty() {
    return this == EMPTY || this.item == Items.AIR || this.count <= 0;
}

This has an impact in the protocol

public PacketByteBuf writeItemStack(ItemStack stack) {
    if (stack.isEmpty()) {
        this.writeBoolean(false);
    } else {
        this.writeBoolean(true);
        Item item = stack.getItem();
        this.writeRegistryValue(Registries.ITEM, item);
        this.writeByte(stack.getCount());
        NbtCompound nbtCompound = null;
        if (item.isDamageable() || item.isNbtSynced()) {
            nbtCompound = stack.getNbt();
        }
        this.writeNbt(nbtCompound);
    }
    return this;
}

What solution would you like?

• Replace all occurrences of Option<ItemStack> with ItemStack.
• Add is_empty method to ItemStack with same semantics as vanilla isEmpty.
• Make the item count in ItemStack public and an i8.
• impl {Encode, Decode} for ItemStack.

[dyc3]

Makes sense. This could make inventories easier to work with.

[IoaNNUwU]

I'll give it a try.