Fatal error: Uncaught Error: Call to undefined function is_admin() in /users/laufgruppe-lvb/www/wordpress/wp-content/plugins/eventon-seats/includes/admin/class-seat-map-editor.php:1074 Stack trace: #0 {main} thrown in /users/laufgruppe-lvb/www/wordpress/wp-content/plugins/eventon-seats/includes/admin/class-seat-map-editor.php on line 1074