With an application this mature reality is I could have coded out any view on the command line of errors that Class Viewer encounters but you can see a big splash if, for instance, Class Viewer can't open the browser or something which goes back to me being bothered when I'd be looking at code which would just do nothing, while crashing mightily inside. So it's just a personal preference. To me my job is to make sure that if used correctly with everything setup correctly, there should be no errors. Perfect code.
So if you see a big splash of exception errors? That should be a configuration problem. Where I left it that way rather than either have it not appear if I missed it, or just have Class Viewer politely inform you.