forms - Symfony2：奇妙なフォームの振る舞い

Question

symfony2ユーザーリセットパスワードのリセットアクションを書きました。コードは次のとおりです。

/**
 * @Route("/reset-password/{confirmationToken}", name="user_resetting_confirm")
 * @ParamConverter("confirmationToken", class="MyProjectBundle:User")
 * @param \My\Project\Entity\User $user
 * @Template()
 */
public function resetAction(Request $request, $confirmationToken)
{
    $form = $this->createFormBuilder()
            ->add('password', 'repeated', array(
                    'type' => 'password',
                    'first_name' => 'New Password',
                    'second_name' => 'Confirm New Password',
                    'invalid_message' => 'Passwords don\'t match',
                    'error_bubbling' => true,
                ))
    ->getForm();

    if ('POST' == $request->getMethod()) {
        $form->bindRequest($request);
        $data = $form->getData();


        $user = $this->container->get('fos_user.user_manager')->findUserByConfirmationToken($confirmationToken);

        if (null === $user) {
            throw new NotFoundHttpException(sprintf('The user with "confirmation token" does not exist for value "%s"', $confirmationToken));
        }

        if (!$user->isPasswordRequestNonExpired($this->container->getParameter('fos_user.resetting.token_ttl'))) {
            return new RedirectResponse($this->container->get('router')->generate('fos_user_resetting_request'));
        }

        if ($form->isValid()) {
            $newPassword = $data['password'];

            $factory = $this->get('security.encoder_factory');
            $encoder = $factory->getEncoder($user);
            $password = $encoder->encodePassword($newPassword, $user->getSalt());
            $user->setPassword($password);
            $em = $this->get('doctrine')->getEntityManager();
            $em->persist($user);
            $em->flush();
            $this->authenticateUser($user);
            return new RedirectResponse($this->getRedirectionUrl($user));
        }
    }

    return $this->render('MyProjectBundle:Resetting:password_reset.html.twig',array('form' => $form->createView()));

}

何らかの理由で、両方のフィールドに間違ったパスワードを入力してから送信すると、HTMLコードのない空白のページが表示されます。ここで何か間違っていることはありますか？