Fatal error: Uncaught Error: Using $this when not in object context in /home/malvernj/public_html/wp-content/plugins/event-tickets/src/views/registration/button-cart.php:17 Stack trace: #0 {main} thrown in /home/malvernj/public_html/wp-content/plugins/event-tickets/src/views/registration/button-cart.php on line 17