Fix NoMethodError when Slack is unavailable

[sonicdoe]

When Slack is experiencing connectivity issues and returns a 503 Service Unavailable, slack-ruby-client should throw a Faraday::ClientError. However, due to

slack-ruby-client/lib/slack/web/faraday/response/raise_error.rb

Line 12 in ffe7ec8

raise Slack::Web::Api::Errors::SlackError.new(body['error'], env.response)

a NoMethodError: undefined method `[]' for nil:NilClass is raised (since body is nil). The same error was also reported in #32.

I haven’t looked into an actual fix yet but I figured submitting a failing test would help 🙂

[dblock]

Good call! We generally need to handle 50x error codes differently from 40x error codes that contain a JSON body.

[sonicdoe]

By the way, that’s also on the roadmap for Faraday v1.0 (see lostisland/faraday#735).

[sonicdoe]

I’ve now fixed the NoMethodError by changing the logic in raise_error.rb. It now raises a SlackError only if body['ok'] is false. If body is nil, the response will fall through to ::Faraday::Response::RaiseError which will then raise a Faraday::ClientError.

[dblock]

Perfect, care to rebase this please and I'll merge. Maybe describe error handling in README if you think it can be helpful to others, too.

[jmanian]

bump

[dblock]

Thanks, sorry didn't get a notification on rebase.

[sonicdoe]

Maybe describe error handling in README if you think it can be helpful to others, too.

I’ve now opened #190 which documents all of slack-ruby-client’s error handling.