[Spreed] Token error

Hello,

I’m running Nextcloud 12 and enabled the ‘video call’ app and tried to call another user. During that process, an error site showed up and I obtained the following log:

	Symfony\Component\Routing\Exception\InvalidParameterException: Parameter "token" for route "spreed.pagecontroller.showCall" must match "[^/]++" ("" given) to generate a corresponding URL.

    /var/www/owncloud/3rdparty/symfony/routing/Generator/UrlGenerator.php - line 136: Symfony\Component\Routing\Generator\UrlGenerator->doGenerate(Array, Array, Array, Array, Array, 'spreed.pagecont...', 1, Array, Array)
    /var/www/owncloud/lib/private/Route/Router.php - line 339: Symfony\Component\Routing\Generator\UrlGenerator->generate('spreed.pagecont...', Array, 1)
    /var/www/owncloud/lib/private/Route/CachingRouter.php - line 60: OC\Route\Router->generate('spreed.pagecont...', Array, false)
    /var/www/owncloud/lib/private/URLGenerator.php - line 70: OC\Route\CachingRouter->generate('spreed.pagecont...', Array)
    /var/www/owncloud/apps/spreed/lib/Controller/PageController.php - line 135: OC\URLGenerator->linkToRoute('spreed.pagecont...', Array)
    [internal function] OCA\Spreed\Controller\PageController->index('', 'XXX')
    /var/www/owncloud/lib/private/AppFramework/Http/Dispatcher.php - line 160: call_user_func_array(Array, Array)
    /var/www/owncloud/lib/private/AppFramework/Http/Dispatcher.php - line 90: OC\AppFramework\Http\Dispatcher->executeController(Object(OCA\Spreed\Controller\PageController), 'index')
    /var/www/owncloud/lib/private/AppFramework/App.php - line 114: OC\AppFramework\Http\Dispatcher->dispatch(Object(OCA\Spreed\Controller\PageController), 'index')
    /var/www/owncloud/lib/private/AppFramework/Routing/RouteActionHandler.php - line 47: OC\AppFramework\App main('PageController', 'index', Object(OC\AppFramework\DependencyInjection\DIContainer), Array)
    [internal function] OC\AppFramework\Routing\RouteActionHandler->__invoke(Array)
    /var/www/owncloud/lib/private/Route/Router.php - line 299: call_user_func(Object(OC\AppFramework\Routing\RouteActionHandler), Array)
    /var/www/owncloud/lib/base.php - line 1000: OC\Route\Router->match('/apps/spreed/')
    /var/www/owncloud/index.php - line 40: OC handleRequest()
    {main}

Do I have misconfigured something or is possible that this is a bug?

P.S.: In Nextcloud, only the default STUN server is configured (no TURN server)