Incompatibility between Faraday >= 2.7.0 and bin/slack script including GLI::App at the top level

[blowfishpro]

Steps to Reproduce

• Have faraday >= 2.7.0 installed
• Run the bin/slack command in some way that would produce an error
  • slack --vcr-cassette-name=web/auth_test_error --slack-api-token=token auth test from the test suite will do

Observed behavior You get an error message: error: wrong number of arguments (given 1, expected 0)

Desired behavior You get the actual error message, e.g. error: not_authed

Explanation

• The slack script includes GLI::App at the top level
  • This unfortunately includes GLI::App in the Object class:

    $ ruby -e 'module M; end; include M; puts Object.ancestors.inspect'
    [Object, M, Kernel, BasicObject]

• Faraday::Middleware calls on_error on itself with an exception it that method is implemented
• This resolves to GLI::App#on_error which has a completely different meaning

Possible Fixes

• replace include GLI::App with extend GLI::App ... all the tests seem to pass with this change (in this case it's included in the singleton class of the main object rather than Object)
• Wrap the whole CLI in a class that has extend GLI::App (this seems to be what GLI's docs mostly reference)

[dblock]

I think we want to wrap the whole CLI to make it future-proof, aka your second option. Want to PR?

[blowfishpro]

I think that would involve wrapping everything in bin/commands in module(s) - it would be a lot of changes but relatively straightforward. I can do that if that sounds reasonable.

[dblock]

@blowfishpro Sounds reasonable I think! Thanks.