SkillDialog not working for non-'expected replies' scenario

[axelsrz]

Version

4.8.0

Describe the bug

SkillDialog won't work out of the box for non expected-replies scenarios.

To Reproduce

Steps to reproduce the behavior:

1. Set up a root bot using skill dialog and a skill bot
2. Run both bots and initiate the SkillDialog
3. When the skill first comes back to the parent an error like the following should arise:

File "..path-to-botbuilder/botbuilder-python/libraries/botbuilder-dialogs/botbuilder/dialogs/skills/skill_dialog.py", line 213, in _send_to_skill
    if not 200 <= response.status <= 299:
AttributeError: 'NoneType' object has no attribute 'status'

Expected behavior

The response get back to the parent without any problems

Workaround

If the skill bot is modified to always send some content in every successful response at the route handler level, the scenario should work.

Example on how to do this for an aiohttp skill bot:

#This is how a typical message handler method could look like
async def messages(req: Request) -> Response:
    # Main bot message handler.
    if "application/json" in req.headers["Content-Type"]:
        body = await req.json()
    else:
        return Response(status=415)

    activity = Activity().deserialize(body)
    auth_header = req.headers["Authorization"] if "Authorization" in req.headers else ""

    response = await ADAPTER.process_activity(activity, auth_header, BOT.on_turn)
    if response:
        return json_response(data=response.body, status=response.status)
    # THE FIX IS IN THE LINE BELOW
    return Response(status=201, body='{"foo":"bar"}'.encode("utf-8"))

Alternative Workaround: use expected replies as delivery method in the parent bot (SkillDialog).

[bug]