File "electrum\gui\qt\network_dialog.py", line 425, in set_proxy
  File "electrum\network.py", line 392, in run_from_another_thread
  File "concurrent\futures\_base.py", line 439, in result
  File "concurrent\futures\_base.py", line 388, in __get_result
  File "electrum\util.py", line 1093, in wrapper
  File "electrum\network.py", line 622, in set_parameters
  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 261, in save_user_config