SO TypeError: 'NoneType' object is not subscriptable

[bitphage]

Traceback (most recent call last):
  File "/home/vvk/devel/DEXBot-prod/dexbot/worker.py", line 131, in on_block
    self.workers[worker_name].ontick(data)
  File "/home/vvk/.local/share/virtualenvs/DEXBot-prod-N9mtHQyI/lib/python3.7/site-packages/events/events.py", line 95, in __call__
    f(*a, **kw)
  File "/home/vvk/devel/DEXBot-prod/dexbot/strategies/staggered_orders.py", line 2210, in tick
    self.maintain_strategy()
  File "/home/vvk/devel/DEXBot-prod/dexbot/decorators.py", line 19, in wrapper
    func(self, *args, **kwargs)
  File "/home/vvk/devel/DEXBot-prod/dexbot/strategies/staggered_orders.py", line 205, in maintain_strategy
    order_ids = [result[1] for result in trx['operation_results']]
TypeError: 'NoneType' object is not subscriptable