File "electrum/gui/qt/main_window.py", line 1632, in do_pay
  File "electrum/gui/qt/main_window.py", line 1646, in do_pay_invoice
  File "electrum/gui/qt/main_window.py", line 1696, in pay_onchain_dialog
  File "electrum/gui/qt/confirm_tx_dialog.py", line 118, in have_enough_funds_assuming_zero_fees
  File "electrum/gui/qt/main_window.py", line 1685, in <lambda>
  File "electrum/wallet.py", line 1384, in make_unsigned_transaction
  File "electrum/coinchooser.py", line 332, in make_tx
  File "electrum/coinchooser.py", line 427, in choose_buckets
  File "electrum/coinchooser.py", line 427, in <listcomp>
  File "electrum/coinchooser.py", line 456, in penalty
  File "electrum/coinchooser.py", line 321, in tx_from_buckets
  File "electrum/coinchooser.py", line 235, in _construct_tx_from_selected_buckets