hanyuu/templates/errors/master.php

<?php
$self->extends('master');

$self->block('body', function($self) {
?>
    <div class="http-err">
        <h1 class="http-err-title"><?=($self->http_error_title ?? 'Unknown Error');?></h1>
        <p class="http-err-paragraph"><?=($self->http_error_desc ?? 'No additional information is available.');?></p>
    </div>
<?php
});