Remove useless return

(cherry picked from commit 2875e05)

qubesmanager/qube_manager.py

@@ -1597,7 +1597,6 @@ def open_settings(self, vm, tab='basic'):
                     "Qube settings cannot be opened. The qube might have "
                     "been removed or unavailable due to policy settings."
                     "\nError: {}".format(str(ex))))
-            return
 
     def closeEvent(self, _):
         self.save_showing()