File "electrum/gui/qt/main_window.py", line 3257, in closeEvent
  File "electrum/gui/qt/main_window.py", line 3278, in clean_up
  File "electrum/gui/qt/__init__.py", line 307, in close_window
  File "electrum/daemon.py", line 286, in stop_wallet
  File "electrum/wallet.py", line 240, in stop_threads
  File "electrum/util.py", line 356, in <lambda>
  File "electrum/util.py", line 352, in do_profile
  File "electrum/storage.py", line 89, in write
  File "electrum/storage.py", line 105, in _write