Traceback (most recent call last):
  File "/media/sf_/Electrum-4.5.8/electrum/gui/qt/channel_details.py", line 276, in closeEvent
    self.unregister_callbacks()
    ~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/media/sf_/Electrum-4.5.8/electrum/gui/qt/util.py", line 1436, in unregister_callbacks
    self.qt_callback_signal.disconnect()
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
TypeError: disconnect() failed between 'qt_callback_signal' and all its connections