[Hummingbird] Page Caching module adds PHP code to the source code of the site

When I check the source code of my site, I notice the following string at the top:
<?php die(); ?>
this comes from Hummingbird wp-content/plugins/wp-hummingbird/core/modules/class-page-cache.php line 1204
I replaced

if ( preg_match( '/.php/', basename( $wphb_cache_file ) ) && ! $is_404 ) {
$content = '<?php die(); ?>' . $content;
}

with

if ( preg_match( '/.php/', basename( $wphb_cache_file ) ) && ! $is_404 ) {
$content = $content;
}

and now its fine. Could you fix this in upcoming versions of the plugin?