XUI fails to load partial potential issue with webpacks

Bug description

In testing sometimes the Login page fails to fully pull back all xui elements and the Username and Password fields fail to load. 

There is an unhandled promise rejection for "the paritial login/_SelfSerivice could not be found

How to reproduce the issue

1. Try to access the server multiple times. 
2. Customer can only reproduce in rare cases with automation checking if server is up. 

Expected behaviour

the login page would have username and password fields

Current behaviour

In rare cases these fields will not load

Work around

reload the page

Code analysis

From discussing internally this looks similar but there are several changes where this would not apply to 6x

“OPENAM-14542 Ensure Partials Are Preloaded”