Fix #874: Enable using BoltJS without passing a botId

[misscoded]

Summary

Fixes #874

Currently, when using an app that only makes use of a user token, the ignoreSelf middleware will throw an error because it expects a botId to always be present.

This PR removes the error thrown (and corresponding test) if a botId is not present in the incoming event's payload.

Requirements (place an x in each [ ])

• 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.

[codecov]

Codecov Report

Merging #1087 (3141cce) into main (926b669) will decrease coverage by 0.04%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #1087      +/-   ##
==========================================
- Coverage   71.01%   70.96%   -0.05%     
==========================================
  Files          13       13              
  Lines        1235     1233       -2     
  Branches      362      361       -1     
==========================================
- Hits          877      875       -2     
  Misses        288      288              
  Partials       70       70              

Impacted Files	Coverage Δ
src/middleware/builtin.ts	83.84% <ø> (-0.25%)	⬇️

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[seratch]

Looks good to me. Perhaps, you've already verified that App initialized with a user token now works fine but if not, we can manually check the pattern before merging this PR. If we can add some tests for the pattern, that's a great addition! but it's not a must this time.

[seratch]

Yes, we can safely remove this one. Also, as the other tests cover all the patterns in this test group, we don't need to add any tests this time.

[seratch]

This one is ready for merge but let's hold off merging until we merge #1024

[misscoded]

If we can add some tests for the pattern

@seratch Good call. When pulling in the latest changes, I revisited and added a test case for the pattern of only passing in a botUserId. I believe the existing test cases cover the other possible scenarios, but if there are others that I've overlooked that you think would be useful, let me know -- happy to add them!

[seratch]

@misscoded Thanks, the test also looks good to me 👍