Fatal error: Uncaught Error: Call to a member function process_payment() on null in /home/customer/www/karessmcgrath.com/public_html/wp-content/plugins/sprout-invoices-pro/controllers/checkout/Checkouts.php:423 Stack trace: #0 /home/customer/www/karessmcgrath.com/public_html/wp-content/plugins/sprout-invoices-pro/controllers/checkout/Checkouts.php(136): SI_Checkouts->complete_checkout() #1 /home/customer/www/karessmcgrath.com/public_html/wp-content/plugins/sprout-invoices-pro/controllers/checkout/Checkouts.php(81): SI_Checkouts->handle_action('payment') #2 /home/customer/www/karessmcgrath.com/public_html/wp-content/plugins/sprout-invoices-pro/controllers/checkout/Checkouts.php(70): SI_Checkouts->__construct() #3 /home/customer/www/karessmcgrath.com/public_html/wp-content/plugins/sprout-invoices-pro/controllers/checkout/Checkouts.php(49): SI_Checkouts::get_instance() #4 /home/customer/www/karessmcgrath.com/public_html/wp-content/plugins/sprout-invoices-pro/controllers/_Controller.php(453): SI_Checkouts::checkout(Object(WP) in /home/customer/www/karessmcgrath.com/public_html/wp-content/plugins/sprout-invoices-pro/controllers/checkout/Checkouts.php on line 423