How to make a custom comment file upload field required?

How to make a custom comment file upload field required?

I have so far build and integrated the file upload in comment field via filter now I WANT TO make it a required field I tried the class="required" not working then i tried the other hook method as defined but so far its not a field of text its not working either
     function custom_validate_comment() {
 //validate for brief and rating
   if( empty( $_POST['image']) )
    wp_die( __('Error: you must upload an image') );
    //make comment not required

       add_action('pre_comment_on_post', 'custom_validate_comment');