wp > Search & Filter > empty result redirect

<?php

    /*
    * redirect when search & find is empty
    */
    if(isset($_GET['post_types'])) {
        $var = $_GET['post_types'];
        if($var == 'publication'){
            //echo 'pub';
            wp_safe_redirect( ''.get_home_url().'/publication' ); exit;
        }else if ($var == 'project'){
            //echo 'pro';
            wp_safe_redirect( ''.get_home_url().'/projects' ); exit;
        }
    }