Fix Vault Economy Max Balance Oversight#145

Most Vault economy provider plugins will have a configured maximum balance. If Vault’s depositPlayer method would result in the player’s balance exceeding the maximum, it should return an EconomyResponse object, whose ResponseType is ResponseType.FAILURE.

In testing, ShopGUI+ does not seem to check this before calling the depositPlayer method when a player sells an item, meaning the money is not deposited into the player’s account, but the sold item is removed from the player’s inventory.

ShopGUI+ should check for ResponseType.SUCCESS before completing a transaction.