UnauthorizedHttpException first argument should be a String

[ellalderton]

In the authenticate method in the Nodes\Backend\Auth\Providers\Session.php the UnauthorizedHttpException first argument is null, but the first argument needs to be string.

class UnauthorizedHttpException extends HttpException
{
    /**
     * @param string     $challenge WWW-Authenticate challenge string
     * @param string     $message   The internal exception message
     * @param \Throwable $previous  The previous exception
     * @param int        $code      The internal exception code
     */
    public function __construct(string $challenge, string $message = null, \Throwable $previous = null, ?int $code = 0, array $headers = [])
    {
        $headers['WWW-Authenticate'] = $challenge;

        parent::__construct(401, $message, $previous, $headers, $code);
    }
}

[sebastianlyserena]

This should be resolved by #155