File "electrum/gui/qt/main_window.py", line 1584, in do_pay
  File "electrum/wallet.py", line 747, in save_invoice
  File "electrum/wallet.py", line 293, in save_db
  File "electrum/wallet_db.py", line 1224, in write
  File "electrum/wallet_db.py", line 1232, in _write
  File "electrum/util.py", line 406, in <lambda>
  File "electrum/util.py", line 402, in do_profile
  File "electrum/storage.py", line 85, in write