Setting baseURL in Registrar not working

The fatal error results by not setting the baseUrl in App.php because i'd like to only set it inside Registrar. Seems like it _must_ be initially set in App.php anyway.

After further investigation i've found out that the method App() is not listed as callable inside 

"vendor\codeigniter4\framework\system\Config\BaseConfig.php" :

PHP Code:

// ignore non-applicable registrars
if (! method_exists($callable, $shortName)) {
  continue; // @codeCoverageIgnore
  } 


--> lists the following methods as callable:

Exceptions
ContentSecurityPolicy
Cache
UserAgents
Cookie
Toolbar
Logger
Auth
Routing
Filters
AuthRoutes

So that seems like the reason why it never gets called and the constructor of the Registrar does. 
Don't know why it is working in your setup, please check by adding a "die()" inside the App() method of the Registrar.