And indeed this solution: Angular 8 isAuthenticated race condition once again proves to be a superior and more flexible implementation than the Angular SPA Start guide, and you should strongly consider updating that guide to reflect the tweaks he makes here. This implementation both accomplishes what’s already handled well by your Angular guide (applications w/ both authenticated and publically-accessible portions) while also handling Angular applications with no public-facing content, which your guide does NOT do (it produces either a recursive login loop or requires 2-3 logins looped before allowing access, depending on the redirect scheme: for that poster, it was 2, because he had a static landing URI, whereas for me it looped infinitely (because I tried to support the user logging back into any route within the app).
I wish that you would allow wildcards when configuring allowable callback URLs.