Handle export failures better

- Ensure collection reopened even on failure
- Don't display a traceback to the user

qt/aqt/exporting.py

@@ -171,8 +171,12 @@ class ExportDialog(QDialog):
             def on_done(future: Future) -> None:
                 self.mw.progress.finish()
                 hooks.media_files_did_export.remove(exported_media)
+                try:
                     # raises if exporter failed
                     future.result()
+                except Exception as e:
+                    traceback.print_exc(file=sys.stdout)
+                    showWarning(str(e))
                 self.on_export_finished()
 
             self.mw.progress.start()