为什么会出现此错误：未定义的属性：PHP中的Twig_Environment？

I am getting this error: Notice: Undefined property: Twig_Environment::$render in when trying to send a message from a PHP-file to a twig-file when is wrong login. I want to show the same page with the message from mu PHP-file like that:

$twig = new Twig_Environment($loader);
echo $twig->render('register.twig');

if (isset($_POST['reg'])) {

    if ($_POST['pwd1'] === $_POST['pwd2']) {

    } else {
        echo ("<script>location.href = $twig->render('register.twig', array('theMessage' => 'Wrong password!'));</script>");
        exit;
    }
}

and in twig-file:

{% if theMessage %}
  {{ theMessage }}
{% endif %} 

But it doesn't work and I get the error above. I am having big trouble to try to resolve it. I am open to any suggestions or hint.

The problem is that PHP is interpolating the $twig variable inside your message. It's better to change this code:

echo ("<script>location.href = $twig->render('register.twig', array('theMessage' => 'Wrong password!'));</script>");

To this one:

echo sprintf("<script>location.href = %s;</script>", $twig->render('register.twig', array('theMessage' => 'Wrong password!')));