File "electrum\gui\qt\main_window.py", line 3191, in closeEvent
  File "electrum\gui\qt\main_window.py", line 3202, in clean_up
  File "electrum\simple_config.py", line 159, in set_key
  File "electrum\simple_config.py", line 168, in _set_key_in_user_config
  File "electrum\simple_config.py", line 260, in save_user_config