Provide UI feedback on error view when new message or new page is loading

[alechenninger]

When continuously selecting error messages, it's difficult to know whether the next selection looks the exact same or if the application is just not yet done loading the next message. The only way to tell is to look at the spinner at the top of the screen, but it'd be nice to have that feedback right over the error view pane itself, by either greying out what is there, showing a spinner over what is there, or just removing what it is there, etc.

[alechenninger]

I also found scrolling between pages has a similar frustration.