Fatal error: Uncaught Error: Call to a member function add_setting() on null in /home/aniografia/public_html/lekcjatest11at/wp-content/themes/sydney/inc/customizer/options/upsell.php:11 Stack trace: #0 {main} thrown in /home/aniografia/public_html/lekcjatest11at/wp-content/themes/sydney/inc/customizer/options/upsell.php on line 11