Portal App: we sometimes get invalid DomEvents: addDomListener() calls when navigating from Home to Learn

This one is interesting for multiple reasons:

• I did not scroll on the Home Page
• Yet we do get events from the Colors App, which only gets mounted in case we scroll down to that page
• Meaning: there must be an IntersectionObserver match when moving the node

To resolve this:

• We need to add a check to only switch code.LivePreviews to the preview tab, in case the view is still the active one and in case the route is still home (has to be mounted).