Ensure that the inventory is not empty before interacting with an item

squirrelbattle/game.py

@@ -123,13 +123,19 @@ class Game:
             self.inventory_menu.go_up()
         elif key == KeyValues.DOWN:
             self.inventory_menu.go_down()
-        elif key == KeyValues.USE:
+        if self.inventory_menu.values:
+            if key == KeyValues.USE:
                 self.inventory_menu.validate().use()
             elif key == KeyValues.EQUIP:
                 self.inventory_menu.validate().equip()
             elif key == KeyValues.DROP:
                 self.inventory_menu.validate().use()
 
+            # Ensure that the cursor has a good position
+            self.inventory_menu.position = min(self.inventory_menu.position,
+                                               len(self.inventory_menu.values)
+                                               - 1)
+
     def handle_key_pressed_main_menu(self, key: KeyValues) -> None:
         """
         In the main menu, we can navigate through options.