Fix adding list of items to inventory

Author: bensku

src/main/java/ch/njol/skript/classes/data/DefaultChangers.java

@@ -221,7 +221,7 @@ public void change(final Inventory[] invis, final @Nullable Object[] delta, fina
 					case ADD:
 						assert delta != null;
 
-						if(delta instanceof ItemStack[]) { // Old behavior - legacy code
+						if(delta instanceof ItemStack[]) { // Old behavior - legacy code (is it used? no idea)
 							ItemStack[] items = (ItemStack[]) delta;
 							if(items.length > 36) {
 								return;
@@ -236,11 +236,20 @@ public void change(final Inventory[] invis, final @Nullable Object[] delta, fina
 									((ItemType) d).addTo(invi);
 								}
 							}
-						} else if (delta instanceof ItemType[]) {
+						} else {
 							for (final Object d : delta) {
-								((ItemType) d).addTo(invi);
+								if (d instanceof ItemStack) {
+									new ItemType((ItemStack) d).addTo(invi); // Can't imagine why would be ItemStack, but just in case...
+								} else if (d instanceof ItemType) {
+									((ItemType) d).addTo(invi);
+								} else if (d instanceof Block) {
+									new ItemType((Block) d).addTo(invi);
+								} else {
+									Skript.error("Can't " + d.toString() + " to an inventory!");
+								}
 							}
 						}
+						
 						break;
 					case REMOVE:
 					case REMOVE_ALL: