Traceback (most recent call last):
  File "electrum\gui\qt\send_tab.py", line 571, in do_pay_or_get_invoice
  File "electrum\gui\qt\send_tab.py", line 514, in read_invoice
  File "electrum\gui\qt\send_tab.py", line 651, in check_payto_line_and_show_errors
  File "electrum\payment_identifier.py", line 670, in has_expired
TypeError: unsupported operand type(s) for +: 'int' and 'NoneType'