Add Checks to other Tools

src/main/java/noppes/npcs/items/ItemNpcTool.java

@@ -157,10 +157,28 @@ public class ItemNpcTool extends Item {
     }
 
     public static boolean isHammer(ItemStack itemStack) {
+        if(itemStack == null)
+            return false;
+
+        if(itemStack.getItem() == null)
+            return false;
+
+        if(!(itemStack.getItem() instanceof ItemNpcTool))
+            return false;
+
         return itemStack.getItemDamage() == 0;
     }
 
     public static boolean isMagicBook(ItemStack itemStack) {
+        if(itemStack == null)
+            return false;
+
+        if(itemStack.getItem() == null)
+            return false;
+
+        if(!(itemStack.getItem() instanceof ItemNpcTool))
+            return false;
+
         return itemStack.getItemDamage() == 2;
     }