Error thrown

Call to undefined function _wp_get_current_user()

Fatal error: Uncaught Error: Call to undefined function delete_user_option() in /mnt/web114/b1/65/5513565/htdocs/WordPress_01/wp-content/plugins/wordpress-seo/admin/class-yoast-notification-center.php:618 Stack trace: #0 /mnt/web114/b1/65/5513565/htdocs/WordPress_01/wp-content/plugins/wordpress-seo/admin/class-yoast-notification-center.php(508): Yoast_Notification_Center->remove_storage() #1 /mnt/web114/b1/65/5513565/htdocs/WordPress_01/wp-includes/class-wp-hook.php(287): Yoast_Notification_Center->update_storage('') #2 /mnt/web114/b1/65/5513565/htdocs/WordPress_01/wp-includes/class-wp-hook.php(311): WP_Hook->apply_filters(NULL, Array) #3 /mnt/web114/b1/65/5513565/htdocs/WordPress_01/wp-includes/plugin.php(484): WP_Hook->do_action(Array) #4 /mnt/web114/b1/65/5513565/htdocs/WordPress_01/wp-includes/load.php(1052): do_action('shutdown') #5 [internal function]: shutdown_action_hook() #6 {main} thrown in /mnt/web114/b1/65/5513565/htdocs/WordPress_01/wp-content/plugins/wordpress-seo/admin/class-yoast-notification-center.php on line 618