File "electrum\util.py", line 879, in run_with_except_hook
  File "threading.py", line 864, in run
  File "electrum\gui\qt\main_window.py", line 2612, in privkeys_thread
  File "electrum\wallet.py", line 367, in export_private_key
  File "electrum\keystore.py", line 381, in get_private_key
  File "electrum\keystore.py", line 346, in get_master_private_key
  File "electrum\crypto.py", line 178, in pw_decode
  File "base64.py", line 80, in b64decode
  File "base64.py", line 46, in _bytes_from_decode_data