--- a/net/minecraft/server/EntityProjectileThrowable.java
+++ b/net/minecraft/server/EntityProjectileThrowable.java
@@ -18,8 +18,8 @@
 
     public void setItem(ItemStack itemstack) {
         if (itemstack.getItem() != this.i() || itemstack.hasTag()) {
-            this.getDataWatcher().set(EntityProjectileThrowable.e, SystemUtils.a((Object) itemstack.cloneItemStack(), (itemstack1) -> {
-                itemstack1.setCount(1);
+            this.getDataWatcher().set(EntityProjectileThrowable.e, SystemUtils.a(itemstack.cloneItemStack(), (itemstack1) -> { // CraftBukkit - decompile error
+                if (!itemstack1.isEmpty()) itemstack1.setCount(1); // CraftBukkit
             }));
         }