Reading RunWorkerCompletedEventArgs.Result rethrows any exception from the
count DoWork. In the Avalonia async void handler this became an unhandled
exception that killed the app during library load (issue #1931). Check
e.Cancelled/e.Error first, log once, and degrade to empty stats in both the
Avalonia and WinForms backup-count completion handlers.
Co-authored-by: rmcrackan <rmcrackan@gmail.com>
