Route not working in one specific situation

Hi all. I added a route to my routes.php to handle a translation button. Two buttons go to the route funcToggleLanguage with the strLanguage parameters. When clicked it will reload the same page but with a newly set language.

The thing is, if I am on the root url, then this doesn’t work. In stead it seems to loop

use Slim\App;
return function (App $app) {    
    $app->get('/', \App\Action\Home\HomeAction::class)->setName('root');
    $app->get('/challenges', \App\Action\Challenge\ChallengeAction::class)->setName('challenges');
    $app->get('/ventures', \App\Action\Venture\VentureAction::class)->setName('ventures');
    $app->get('/{strLanguage}', function ($oRequest, $oResponse, $oArguments) {
        if ($oArguments['strLanguage'] === 'nl') {
            $_SESSION['strLocale'] = 'nl_NL';
        if ($oArguments['strLanguage'] === 'en') {
            $_SESSION['strLocale'] = 'en_US';
        return $oResponse->withRedirect($_SESSION['strRouteFrom'], 302);     

That seems suspicious to me:

I was thinking about it, and replaced it with ‘root’ instead to make sure just a while ago. It gives the same result though. But it could be something related. I’ll do some debugging on it later on.