Fatal error: Uncaught Error: Call to undefined function add_filter() in /home/workings/public_html/hidden/wp-content/plugins/fusion-core/shortcodes/class-checklist.php:16 Stack trace: #0 /home/workings/public_html/hidden/wp-content/plugins/fusion-core/shortcodes/class-checklist.php(227): FusionSC_Checklist->__construct() #1 {main} thrown in /home/workings/public_html/hidden/wp-content/plugins/fusion-core/shortcodes/class-checklist.php on line 16