Wordpress... delete post if external post is deleted

Question

My users provide an external link when the post is created. If the external link is deleted, the local post should also be deleted. To accomplish that, I tried running this code...

function check_external_page_status()
{
if( is_single() )
{
   if(get_field('external_listing_page'))
    {
        $external_url = get_field('external_listing_page');

        function get_http_response_code($external_url) {
            $external_headers = get_headers($external_url);
            return substr($external_headers[0], 9, 3);
        }

        $get_http_response_code = get_http_response_code($external_url);

        if ( $get_http_response_code == 200 ) {
            //echo "OKAY!";
        }
        else
        {
            //echo "Not okay!";
            //echo $get_http_response_code;
            //echo get_the_ID();

            wp_delete_post( get_the_ID(), false );
            wp_redirect( home_url( '/expired-listing/',410 ) );
            exit;
        }       
    }
}
}
add_action( 'template_redirect', 'check_external_page_status' );

...but I get these errors...

Warning: get_headers(): php_network_getaddresses: getaddrinfo failed: Name or service not known in /home/cornwal2/public_html/listings/wp-content/plugins/insert-php/includes/class.execute.snippet.php(390) : eval()'d code on line 12

Warning: get_headers(http://fdsafdsfasd.ca): failed to open stream: php_network_getaddresses: getaddrinfo failed: Name or service not known in /home/cornwal2/public_html/listings/wp-content/plugins/insert-php/includes/class.execute.snippet.php(390) : eval()'d code on line 12

Warning: Cannot modify header information - headers already sent by (output started at /home/cornwal2/public_html/listings/wp-content/plugins/insert-php/includes/class.execute.snippet.php(390) : eval()'d code:12) in /home/cornwal2/public_html/listings/wp-includes/pluggable.php on line 1251

Warning: Cannot modify header information - headers already sent by (output started at /home/cornwal2/public_html/listings/wp-content/plugins/insert-php/includes/class.execute.snippet.php(390) : eval()'d code:12) in /home/cornwal2/public_html/listings/wp-includes/pluggable.php on line 1254

Answer 1

So I figured it out... The first 2 warnings relate to the external page that is not valid. Although the warning is legit, in this case I don't want to see it so I simply turned off the warnings. As for the last warnings, I use a javascript redirect instead of the wp_redirect()

function check_external_page_status()
{
if( is_single() )
{
   if(get_field('external_listing_page'))
    {
        $external_url = get_field('external_listing_page');

        function get_http_response_code($external_url) {
           $external_headers = get_headers($external_url);
            return substr($external_headers[0], 9, 3);
        }

        error_reporting(E_ERROR);
        $get_http_response_code = get_http_response_code($external_url);
        //error_reporting(E_ERROR | E_WARNING | E_PARSE | E_NOTICE);
        error_reporting(E_ERROR | E_WARNING | E_PARSE);

        if ( $get_http_response_code == 200 ) {
            //echo "OKAY!";
        }
        else
        {
            wp_die($external_url."<br>Error:".$get_http_response_code);
            //echo "Not okay!";
            //echo $get_http_response_code;
            //echo get_the_ID();

            wp_delete_post( get_the_ID(), false );
            //wp_redirect( home_url( '/expired-listing/',410 ) );
            echo "<script>window.location.replace('".home_url('/expired-listing/')."');</script>";
            exit;
        }       
    }
}
}
add_action( 'template_redirect', 'check_external_page_status' );