我有一个显示作者最新帖子的页面。但当作者没有帖子时，我会收到一条显示消息

警告：rsort（）要求参数1为数组，在。。。

这里是脚本

function wpmu_latest_post_auther($authorId,$how_many = 10, $how_many_words = 50, $more_text = "[...]", $remove_html = true, $sort_by = \'post_date\') {
global $wpdb;

//first, gat all blog id
$query = "SELECT blog_id FROM $wpdb->blogs WHERE blog_id !=\'1\'";
$blogs = $wpdb->get_col($query);

if ($blogs) {
    //we use blog id to loop post query
    foreach ($blogs as $blog) {
        $blogPostsTable = \'wp_\'.$blog.\'_posts\';

         $db_query = "SELECT $blogPostsTable.ID,
                    $blogPostsTable.post_author,
                    $blogPostsTable.post_title,
                    $blogPostsTable.guid,
                    $blogPostsTable.post_date,
                    $blogPostsTable.post_content,
                    $blogPostsTable.post_modified,
                    $blogPostsTable.comment_count
                    FROM $blogPostsTable WHERE $blogPostsTable.post_status = \'publish\'
                    AND $blogPostsTable.post_author = $authorId 
                    AND $blogPostsTable.post_type = \'post\'";

        $thispos = $wpdb->get_results($db_query);

        foreach($thispos as $thispost) {
        if($sort_by == \'post_date\') {
            $order = $thispost->post_date;
        }
        else{
            $order = $thispost->post_modified;
            }

            $post_dates[]           = $order;
            $post_guids[$order]     = $thispost->guid;
            $blog_IDs[$order]       = $blog;
            $post_IDs[$order]       = $thispost->ID;
            $post_titles[$order]    = $thispost->post_title;
            $post_authors[$order]   = $thispost->post_author;
            $post_contents[$order]  = $thispost->post_content;
            $comments[$order]       = $thispost->comment_count;
            }
        }


    rsort($post_dates);
    $union_results  = array_unique($post_dates);
    $ResultArray    = array_slice($union_results, 0, $how_many);

    foreach ($ResultArray as $date) {
        $ID                 = $post_IDs[$date];
        $blogID             = $blog_IDs[$date];
        $id_author          = $post_authors[$date];
        $post_url           = get_blog_permalink($blog_IDs[$date], $ID);/*$post_guids[$date];*/
        $post_title         = $post_titles[$date];
        $post_content       = $post_contents[$date];
        $post_date          = mysql2date(get_option(\'date_format\'), $date);
        $post_time          = mysql2date(get_option(\'time_format\'), $date);
        $total_comment      = $comments[$date];
        $user_info          = get_userdata($id_author);
        $author_blog_url    = get_blogaddress_by_id($user_info->primary_blog);
        $author_url         = $user_info->user_url;
        $author_email       = $user_info->user_email;

        if($user_info->first_name) {
            $author_name = $user_info->first_name.\' \'.$user_info->last_name;
        }
        else{
            $author_name = $user_info->nickname;
        }

        if($remove_html) {
            $post_content = wpmu_cleanup_post($post_content);
        }

        $results = array();

        $results[\'ID\']              = $ID;
        $results[\'blogID\']          = $blogID;
        $results[\'post_url\']        = $post_url;
        $results[\'post_title\']      = $post_title;
        $results[\'post_content\']    = wpmu_cut_article_by_words($post_content, $how_many_words);
        if ($results[\'post_content\'] != $post_content)
            $results[\'post_content\'] .= sprintf(\'  <a href="%s">%s</a>\', $post_url, $more_text);
        $results[\'author_blog_url\'] = $author_blog_url;
        $results[\'author_url\']      = $author_url;
        $results[\'author_email\']    = $author_email;
        $results[\'author_name\']     = $author_name;
        $results[\'post_date\']       = $post_date;
        $results[\'post_time\']       = $post_time;
        $results[\'comment_count\']   = $total_comment;

        $returns[] = $results;
    }

    $latest_posts = wpmu_bind_array_to_object($returns);
    return $latest_posts;
} }

当做