flash.moe/tpl/errors/master.php

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

$self->block('container', function($self) {
?>
    <div class="http-error">
        <h2 class="http-error-head"><?=($self->http_error_title ?? ('Unknown Error #' . $self->http_error_code));?></h2>
        <?php if(isset($self->http_error_image)): ?>
        <img src="<?=$self->http_error_image;?>" alt="<?=$self->http_error_image;?>" class="http-error-image">
        <?php endif; ?>
        <div class="http-error-desc"><?=($self->http_error_desc ?? 'No additional information is available.');?></div>
    </div>
<?php
});