slack-machine crashes with error wrong value type for field "topic.creator" - should be "str" instead of value "None"

[michaelbutler]

Hi, I'm trying to test out slack-machine. I'm on Python 3.7 with latest version installed: Version: 0.20.1.

I only have the HelloPlugin enabled, when I run slack-machine in DEBUG mode I see a lot of API requests going through successfully, it appears to be paginating through channels and users and conversations, however it always gets to this point and crashes with error:

[2020-08-05 19:04:36][ERROR] slack.rtm.client client.py:_dispatch_event:505 | When calling '#_on_open()' in the 'machine.clients.singletons.slack' module the following error was raised: wrong value type for field "topic.creator" - should be "str" instead of value "None" of type "NoneType"
Traceback (most recent call last):
  File "/usr/local/bin/slack-machine", line 8, in <module>
    sys.exit(main())
  File "/usr/local/lib/python3.7/site-packages/machine/bin/run.py", line 14, in main
    bot.run()
  File "/usr/local/lib/python3.7/site-packages/machine/core.py", line 211, in run
    self._dispatcher.start()
  File "/usr/local/lib/python3.7/site-packages/machine/dispatch.py", line 34, in start
    self._client.start()
  File "/usr/local/lib/python3.7/site-packages/machine/clients/singletons/slack.py", line 121, in start
    self.rtm_client.start()
  File "/usr/local/lib/python3.7/site-packages/slack/rtm/client.py", line 206, in start
    return self._event_loop.run_until_complete(future)
  File "/usr/local/Cellar/python/3.7.7/Frameworks/Python.framework/Versions/3.7/lib/python3.7/asyncio/base_events.py", line 587, in run_until_complete
    return future.result()
  File "/usr/local/lib/python3.7/site-packages/slack/rtm/client.py", line 361, in _connect_and_read
    await self._dispatch_event(event="open", data=data)
  File "/usr/local/lib/python3.7/site-packages/slack/rtm/client.py", line 500, in _dispatch_event
    callback(**payload)
  File "/usr/local/lib/python3.7/site-packages/machine/clients/singletons/slack.py", line 74, in _on_open
    self._register_channel(c)
  File "/usr/local/lib/python3.7/site-packages/machine/clients/singletons/slack.py", line 49, in _register_channel
    channel = Channel.from_api_response(channel_response)
  File "/usr/local/lib/python3.7/site-packages/machine/models/channel.py", line 50, in from_api_response
    return from_dict(data_class=Channel, data=user_reponse)
  File "/usr/local/lib/python3.7/site-packages/dacite/core.py", line 60, in from_dict
    value = _build_value(type_=field.type, data=transformed_value, config=config)
  File "/usr/local/lib/python3.7/site-packages/dacite/core.py", line 83, in _build_value
    return _build_value_for_union(union=type_, data=data, config=config)
  File "/usr/local/lib/python3.7/site-packages/dacite/core.py", line 94, in _build_value_for_union
    return _build_value(type_=types[0], data=data, config=config)
  File "/usr/local/lib/python3.7/site-packages/dacite/core.py", line 87, in _build_value
    return from_dict(data_class=type_, data=data, config=config)
  File "/usr/local/lib/python3.7/site-packages/dacite/core.py", line 65, in from_dict
    raise WrongTypeError(field_path=field.name, field_type=field.type, value=value)
dacite.exceptions.WrongTypeError: wrong value type for field "topic.creator" - should be "str" instead of value "None" of type "NoneType"

I'm guessing this is a simple case of the Slack API returning something that we didn't expect, so I guess slack-machine must be made to treat topic.creator as None or even handling the fact that it might not exist. If you have any ideas how I could fix this locally please let me know.

[michaelbutler]

When looking through slack API docs, I'm wondering if this could happen when the user who initially setTopic
on the conversation or channel is a deleted user. I mean it probably still should be empty string "" but for whatever reason maybe they returned null or not anything at all.

[DonDebonair]

Yep, that could be it. In any case, the fix it easy. I'll make the creator optional.

[drdarina]

Has this been fixed? I'm also getting the same error

[eguven]

I'm wondering if this could happen when the user who initially setTopic on the conversation or channel is a deleted user.

@michaelbutler I checked. It was happening on a shared channel where the user who most recently set the topic was still active member of our workspace (so no reason for the value to be None).

I think in our case, the person who setTopic before (member of the other Org) did so prior to sharing the channel and this causes the None. 🤷‍♂️