Improve request parser for better compatibility with Socket Mode

[seratch]

This pull request improves the internals to be �compatible with Socket Mode payloads.

Category (place an x in each of the [ ])

• slack_bolt.App and/or its core components
• slack_bolt.async_app.AsyncApp and/or its core components
• Adapters in slack_bolt.adapter
• Document pages under /docs
• Others

Requirements (place an x in each [ ])

Please read the Contributing guidelines and Code of Conduct before creating this issue or pull request. By submitting, you are agreeing to those rules.

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.
• I've run ./scripts/install_all_and_run_tests.sh after making the changes.

[bharat-rangan]

@seratch - Hi. I am using the slack_bolt package and started getting a new error. Looking at the logs, I traced back to this PR on the same part of the code. I am getting this when I am trying to send a message-shortcut. (I can't pinpoint why the change you made would cause the issue but the timing is curious. Can you please help?

Let me know how I can get more logs to help.

Here is the error.

Exception happened during processing of request from ('127.0.0.1', 44298)
Traceback (most recent call last):
  File "/usr/lib/python3.7/socketserver.py", line 316, in _handle_request_noblock
    self.process_request(request, client_address)
  File "/usr/lib/python3.7/socketserver.py", line 347, in process_request
    self.finish_request(request, client_address)
  File "/usr/lib/python3.7/socketserver.py", line 360, in finish_request
    self.RequestHandlerClass(request, client_address, self)
  File "/usr/lib/python3.7/http/server.py", line 646, in __init__
    super().__init__(*args, **kwargs)
  File "/usr/lib/python3.7/socketserver.py", line 720, in __init__
    self.handle()
  File "/usr/lib/python3.7/http/server.py", line 426, in handle
    self.handle_one_request()
  File "/usr/lib/python3.7/http/server.py", line 414, in handle_one_request
    method()
  File "/app/.local/lib/python3.7/site-packages/slack_bolt/app/app.py", line 881, in do_POST
    body=request_body, query=query, headers=self.headers
  File "/app/.local/lib/python3.7/site-packages/slack_bolt/request/request.py", line 43, in __init__
    self.context = build_context(BoltContext(context if context else {}), self.body)
  File "/app/.local/lib/python3.7/site-packages/slack_bolt/request/internals.py", line 114, in build_context
    enterprise_id = extract_enterprise_id(payload)
  File "/app/.local/lib/python3.7/site-packages/slack_bolt/request/internals.py", line 54, in extract_enterprise_id
    elif "id" in org:
TypeError: argument of type 'NoneType' is not iterable

[seratch]

@bharat-rangan Can you upgrade to v1.1.1? The fix by this PR is included in the version.

[bharat-rangan]

hmm.... I did a force pip-installed and it worked. Sorry if this was a distraction

[bharat-rangan]

aha. Just saw your message. Thanks for contributing to this package :)