Flat item should only write NBT when id != 0

common/src/main/java/us/myles/ViaVersion/api/type/types/minecraft/FlatItemType.java

@@ -18,7 +18,9 @@ public class FlatItemType extends BaseItemType {
             Item item = new Item();
             item.setId(id);
             item.setAmount(buffer.readByte());
+            if (id != 0) {
                 item.setTag(Type.NBT.read(buffer));
+            }
             return item;
         }
     }
@@ -30,7 +32,9 @@ public class FlatItemType extends BaseItemType {
         } else {
             buffer.writeShort(object.getId());
             buffer.writeByte(object.getAmount());
+            if (object.getId() != 0) {
                 Type.NBT.write(buffer, object.getTag());
             }
         }
     }
+}