you can now undo a purchase after buying an item from the shop

Assets/Scripts/Shop.cs

@@ -14,4 +14,36 @@ public class Shop : ItemStorage {
     }
 
     #endregion
+    
+    public bool itemWasBought;
+    
+    private PlayerController _playerController;
+    private Inventory _inventory;
+    private Item _lastBoughtItem;
+    private int _lastBoughtItemAmount;
+
+    /**
+     * Calls ItemStorage.RemoveItem() and sets 2 Variables to remember the last bought item
+     */
+    public override void RemoveItem(Item item, int amount) {
+        base.RemoveItem(item, amount);
+        if(itemWasBought){
+            _lastBoughtItem = item;
+            _lastBoughtItemAmount = amount;
+        }
+    }
+    
+    public void UndoLastPurchase() {
+        if(itemWasBought){
+            _inventory = Inventory.instance;
+            _playerController = PlayerController.instance;
+
+            if(_lastBoughtItem) {
+                _playerController.ChangeMoney(_lastBoughtItem.cost);
+                _inventory.RemoveItem(_lastBoughtItem, _lastBoughtItemAmount);
+                AddItem(_lastBoughtItem, _lastBoughtItemAmount);
+                itemWasBought = false;
+            }
+        }
+    }
 }