core: session ui - Preloading page does not log the fetched user in

[christophercr]

I'm submitting a...

[ ] Regression (a behavior that used to work and stopped working in a new release)
[X] Bug report  
[ ] Feature request
[ ] Documentation issue or request
[ ] Support request => Please do not submit support request here, instead see https://github.com/NationalBankBelgium/stark/blob/master/CONTRIBUTING.md#got-a-question-or-problem

Current behavior

When the Preloading page is shown on PROD, the user profile is correctly fetched but it is not logged in automatically which causes the app to be stuck in the Preloading page since the navigation to the Homepage fails due to the "user not authenticated" error.

Expected behavior

The app should correctly initialize and automatically log the user in on PROD.

Minimal reproduction of the problem with instructions

Run the Showcase in PROD mode with a local backend running.