frontends: async failures are more detailed (full class name + error message)

frontends/src/quick_frontend/quick_app.py

@@ -287,7 +287,7 @@ class QuickApp(object):
         if callback is None:
             callback = lambda: None
         if errback is None:
-            errback = lambda failure: self.showDialog(unicode(failure), _(u"sendMessage Error"), "error")
+            errback = lambda failure: self.showDialog(failure.fullname, failure.message, "error")
         self.bridge.sendMessage(to_jid, message, subject, mess_type, extra, profile_key, callback=callback, errback=errback)
 
     def newAlert(self, msg, title, alert_type, profile):