Change the WordPress > Error title?

Question

I am trying to change the title which is shown in Tabs/Windows when visiting a page you have no access to, where it now says "WordPress > Error".

This is how far I have come, but it doesn't work at all:

add_filter( 'wp_die_handler', 'change_die_wpse_120304' );
function change_die_wpse_120304()
{
    return 'do_wp_die_wpse_120304';
}

function do_wp_die_wpse_120304( $message, $title, $args )
{
    return 'Mynewtitle'.' • '.$title.' ‹ '.get_bloginfo('name'); 
}

I think wp_die_handler has something to do with this, but I cannot find any solution for this.

Answer 1

The wp_die_handler filter filters the handler for the function responsible to kill the execution of the script. So it needs to return the callable that WordPress will use when wp_die() is called.

The actual callable that is returned from the wp_die_handler filter must output the error message and die.

function wpse_die( $message, $title = '', $args = [] ) {
  echo 'yolo';
  die;
}

function wpse_die_handler(){
  return 'wpse_die';
}
add_filter( 'wp_die_handler', 'wpse_die_handler' );

Have a look at _default_wp_die_handler() for a look at what WordPress outputs from the default handler for wp_die().