代码不起作用（.它给我error

<?php

error_reporting(E_ALL);
ini_set('display_errors', 'On');

require_once 'vendor/autoload.php';

use Symfony\Component\Mailer\Exception\TransportExceptionInterface;
use Symfony\Component\Mailer\Transport;
use Symfony\Component\Mailer\Mailer;
use Symfony\Component\Mime\Email;
$transport = Transport::fromDsn('smtp://mymail@gmail.com:MYPASS@smtp.gmail.com:587');

$mailer = new Mailer($transport);
$email = (new Email());
$email->from('mymail@gmail.com');

$email->to('mymail@gmail.com');

$email->subject('Some subject');
$email->text('test-message');

$mailer->send($email);

?>

我试着用这些类“要求”文件，但是没有用。我还检查了我的composer.json。有Symfony，所以我肯定，我有它安装在我的 composer 。