现在要这样

include 'vendor/autoload.php';

if (DEBUG) {

    $Whoops = new \Whoops\Run;

    $title = "哎呀~不小心出错了";

    $option = new \Whoops\Handler\PrettyPageHandler();

    $option->setPageTitle($title);

    $Whoops->pushHandler($option);

    $Whoops->register();

    ini_set('display_errors','On');

} else {

    ini_set('display_errors','Off');

}