Improved NBTData api

src/main/kotlin/net/axay/kspigot/nbt/NBTData.kt

@@ -13,6 +13,10 @@ class NBTData {
         this.nbtTagCompound = nbtTagCompound ?: NBTTagCompound()
     }
 
+    constructor() {
+        this.nbtTagCompound = NBTTagCompound()
+    }
+
     constructor(nbtString: String) : this(MojangsonParser.parse(nbtString))
 
     fun serialize() = nbtTagCompound.toString()

src/main/kotlin/net/axay/kspigot/nbt/NBTDataLoader.kt

@@ -8,11 +8,19 @@ import org.bukkit.entity.Entity
 import org.bukkit.inventory.ItemStack
 
 @NMS_General
-val Entity.nbtData: NBTData get() {
-    val nbtTagCompound = NBTTagCompound()
-    (this as CraftEntity).handle.load(nbtTagCompound)
-    return NBTData(nbtTagCompound)
-}
+var Entity.nbtData: NBTData
+    get() {
+        val nbtTagCompound = NBTTagCompound()
+        (this as CraftEntity).handle.load(nbtTagCompound)
+        return NBTData(nbtTagCompound)
+    }
+    set(value) {
+        (this as CraftEntity).handle.save(value.nbtTagCompound)
+    }
 
 @NMS_General
-val ItemStack.nbtData: NBTData get() = NBTData(CraftItemStack.asNMSCopy(this).tag)
+val ItemStack.nbtData: NBTData get() {
+    CraftItemStack.asNMSCopy(this).let {
+        return if (it.hasTag()) NBTData(it.tag) else NBTData()
+    }
+}