[1.12] some bug?

Code: 

@Override
	public ActionResult<ItemStack> onItemRightClick(World worldIn, EntityPlayer playerIn, EnumHand handIn) {
		if(!worldIn.isRemote) {
			ItemStack itemstack = playerIn.getHeldItem(handIn);
			NBTTagCompound nbt = itemstack.getTagCompound();
			int blood = nbt.hasKey("blood") ? nbt.getInteger("blood") : 0;
			
			if(playerIn.isSneaking()) {
				blood += 2;
				playerIn.attackEntityFrom(BloodLose, 2.0f);
			} else {
				blood -= 5;
				playerIn.setHealth(playerIn.getHealth() + 5.0f);
			}
			nbt.setInteger("blood", blood);
		}
		return super.onItemRightClick(worldIn, playerIn, handIn);
	}

Console:

Caused by: java.lang.NullPointerException
	at TCr.Dark.items.tools.SwordDark.onItemRightClick(SwordDark.java:34) ~[SwordDark.class:?]
	at net.minecraft.item.ItemStack.useItemRightClick(ItemStack.java:234) ~[ItemStack.class:?]
	at net.minecraft.server.management.PlayerInteractionManager.processRightClick(PlayerInteractionManager.java:384) ~[PlayerInteractionManager.class:?]
	at net.minecraft.network.NetHandlerPlayServer.processTryUseItem(NetHandlerPlayServer.java:794) ~[NetHandlerPlayServer.class:?]
	at net.minecraft.network.play.client.CPacketPlayerTryUseItem.processPacket(CPacketPlayerTryUseItem.java:43) ~[CPacketPlayerTryUseItem.class:?]
	at net.minecraft.network.play.client.CPacketPlayerTryUseItem.processPacket(CPacketPlayerTryUseItem.java:9) ~[CPacketPlayerTryUseItem.class:?]
	at net.minecraft.network.PacketThreadUtil$1.run(PacketThreadUtil.java:21) ~[PacketThreadUtil$1.class:?]
	at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) ~[?:1.8.0_151]
	at java.util.concurrent.FutureTask.run(Unknown Source) ~[?:1.8.0_151]
	at net.minecraft.util.Util.runTask(Util.java:53) ~[Util.class:?]
	... 5 more