Error theme PlanShet

Fatal error: Uncaught Error: Call to undefined function create_function() in /public_html/wp-content/themes/planshet/inc/widgets/facebook.php:121 Stack trace: #0 /public_html/wp-content/themes/planshet/functions.php(104): include_once() #1 /public_html/wp-settings.php(555): include('...') #2 /public_html/wp-config.php(98): require_once('...') #3 /public_html/wp-load.php(50): require_once('...') #4 /public_html/wp-admin/admin.php(34): require_once('...') #5 /public_html/wp-admin/customize.php(13): require_once('...') #6 {main} thrown in /public_html/wp-content/themes/planshet/inc/widgets/facebook.php on line 121