File "electrum/gui/qt/main_window.py", line 1571, in do_pay
  File "electrum/wallet.py", line 730, in save_invoice
  File "electrum/wallet.py", line 288, in save_db
  File "electrum/wallet_db.py", line 1216, in write
  File "electrum/wallet_db.py", line 1224, in _write
  File "electrum/util.py", line 390, in <lambda>
  File "electrum/util.py", line 386, in do_profile
  File "electrum/storage.py", line 103, in write