public void BuyUpgrade()
{
if (GameControllerS.I.Money < Cost)
{
throw new System.InvalidOperationException("This method should only be called when clicking the button in shop (which should be only enabled if user has enough money).");
}
GameControllerS.I.SubtractMoney(Cost);
Upgrade.Function(TargetTower);
TargetTower.UpgradeLevels[UpgradeIndex]++;
GameControllerS.I.Shop.LoadTowerInfo(TargetTower);
}
