Check whether a custom taxonomy term has published posts?

function get_issues() {
 $output = array();
 $hlterms = get_terms('issue', array('orderby' => 'id', 'order' => 'DESC','hide_empty' => false));
 foreach($hlterms as $term){
     array_push($output, $term->term_id);
 } 
 return $output;
}

This would return you term id as per the recent and then in your second function start iterating to get the posts for latest issue.

function get_posts_for_current_issue() {
   $total_issues = get_issues();
   foreach($total_issues as $issue_id){
     $args = array(
     'post_type' => 'post',
         'status' => 'publish',
     'tax_query' => array(
          array(
        'taxonomy' => 'issue',
        'field' => 'id',
        'terms' => $issue_id
          )
           )
        );//end of args
     $current_issue_posts = get_posts($args);
     if(!is_wp_error($current_issue_posts) && count($current_issue_posts)>0){
        return $current_issue_posts; //will terminate the loop if posts found
     }
   }//end of foreach
 }//end of function

You might need to turn on the WP_DEBUG, as I can’t test the code.