Bug! Buy products for 0 coins!

Hi there,

i encountered a bug with the current store framework. I dont know if its the store or the store user upgrade plugin, but i was able to subscribe to user upgrade products in the store with 0 coins. Gifting the upgrade worked as expected (not enough founds error).
So i checked the source files and found:

brivium/store/controller/public/product.php

line 33:
$remained = $productPurchaseModel->checkUserMoney($userId, $product, $visitor);
if($remained < 0) {
return $this->responseError(new XenForo_Phrase('BRS_not_enough_money_to_purchase', array('money' => Brivium_Store_EventListeners_Helpers::helperStoreCostFormat($product['cost_amount'], $product['product_id'], $product['money_type'], $product['currency_id'], $product))));
}

EDIT: (stolen from actionGift() on line 85):
if(!$remained = $productPurchaseModel->checkUserMoney($userId, $product, $visitor))
{
return $this->responseError(new XenForo_Phrase('BRS_not_enough_money_to_purchase', array('money' => Brivium_Store_EventListeners_Helpers::helperStoreCostFormat($product['cost_amount'], $product['product_id'], $product['money_type'], $product['currency_id'], $product))));
}


Now it works like a charme
#bugbounty ?

best regards!