Symfony version(s) affected: 4.3.3

Description
I'm trying to pass a variable named 'email' to Twig via ->context(). Causing preg_match() in Generator/UrlGenerator.php:179 to fail with "Warning: preg_match() expects parameter 2 to be string, object given"
Debugging the email var shows, that it somehow became a WrappedTemplatedEmail object.

How to reproduce

$message = (new TemplatedEmail())
                ->subject('...')
                ->from('...')
                ->to($user->getEmail())
                ->textTemplate('...')
                ->context([
                    'email' => $user->getEmail(),
                    'identifier' => urlencode($identifier),
                ])

            $mailer->send($message);

Possible Solution
Renaming the variable 'email' to 'mail' fixes the issue.