获取函数文件中的错误，我无法确定如何修复该错误。错误是：

只能通过引用传递变量

对于以下行：

$user_id = get_comment(get_comment_ID())->user_id;

$user_id = get_comment(get_comment_ID())->user_id;
$user = new WP_User( $user_id );
$user_roles = $user->roles;
$user_role = array_shift($user_roles);

if ($user_role == \'administrator\') {
    echo \'<div class="comment-tag admin-comment-tag">Admin</div><br>\';
} elseif ($user_role == \'contributor\') {
    echo \'<div class="comment-tag contributor-comment-tag">Contributor</div><br>\';
} else {
    echo \' \';
}