File "site-packages\electrum-3.1.1-py3.5.egg\electrum_gui\qt\main_window.py", line 623, in timer_actions
  File "site-packages\electrum-3.1.1-py3.5.egg\electrum_gui\qt\main_window.py", line 743, in update_wallet
  File "site-packages\electrum-3.1.1-py3.5.egg\electrum_gui\qt\main_window.py", line 746, in update_tabs
  File "site-packages\electrum-3.1.1-py3.5.egg\electrum_gui\qt\util.py", line 499, in update
  File "site-packages\electrum-3.1.1-py3.5.egg\electrum\util.py", line 288, in <lambda>
  File "site-packages\electrum-3.1.1-py3.5.egg\electrum\util.py", line 284, in do_profile
  File "site-packages\electrum-3.1.1-py3.5.egg\electrum_gui\qt\history_list.py", line 215, in on_update
  File "site-packages\electrum-3.1.1-py3.5.egg\electrum\util.py", line 288, in <lambda>
  File "site-packages\electrum-3.1.1-py3.5.egg\electrum\util.py", line 284, in do_profile
  File "site-packages\electrum-3.1.1-py3.5.egg\electrum\wallet.py", line 1056, in get_full_history
  File "site-packages\electrum-3.1.1-py3.5.egg\electrum\wallet.py", line 1768, in average_price