Payment with Gift Certificate without Module Installed

I am having an issue with orders being placed and paid with gift certificates even though the module is not installed and don't offer them. It happened rarely in the past but now 3 times in the last week. My site offers 2 different payment methods, PayPal Express Checkout and Square. I even tried renaming the Gift Certificate module but that didn't work. From my very limited knowledge of PHP I found these 2 lines in order.php:

'payment_method' => (($this->info['payment_module_code'] == '' and $this->info['payment_method'] == '') ? PAYMENT_METHOD_GV : $this->info['payment_method']),

'payment_module_code' => (($this->info['payment_module_code'] == '' and $this->info['payment_method'] == '') ? PAYMENT_MODULE_GV : $this->info['payment_module_code']),

Do these lines mean if there is no payment method, then the payment method is PAYMENT_METHOD_GV using PAYMENT_MODULE_GV ?

I don't plan on using gift certificates for my site and would prefer that if there is no payment method then give an error message similar to if no payment method is selected at checkout.

I checked my logs both Zen Cart and Square and there are no errors.

Any assistance is appreciated