Error on keycloak init with an empty page

[denkv]

Description

When there are issues with communicating with Keycloak, the following error may be shown in the console while page stays empty:

error on keycloak init
Error: Uncaught (in promise): [object Null]

https://github.com/hobbit-project/platform/blob/7b6e394ca32ee7a126644956c09350853e79e4bc/hobbit-gui/gui-client/src/app/auth/keycloak.service.ts#L29

Expected behavior

Some error message should appear on the page.