vite wp load critical css

vite-wp-load-critical-css.php

<?php
add_action('wp_head', 'load_critical_css', 0);
function load_critical_css(){

    $dir = FF_DIR .'/dist';
    $handle = 'src/critical.js';

    $manifest = FF\Vite\get_manifest($dir);
    if( !$manifest ) return;

    if( $manifest->is_dev ) {
        // dev, load file
        FF\Vite\enqueue_asset( $dir, $handle, [ 'handle' => $handle, 'in-footer' => false ] );
    } 
    else {
        // production, inline css
        $css_file = $dir.'/'.$manifest->data->$handle->css[0];
        if( !file_exists($css_file) ) return;
        echo '<style type="text/css">'. file_get_contents($css_file) .'</style>';
    }
}