[proposal] Don't retry if no error.code

[reconbot]

I was thinking about my previous issue with testing #187 reading the outcome of #222 and I was looking at the source of is-retry-allowed and the aws-sdk and I realized that we retry on unknown errors, while AWS and possibly others, do not.

I'd like to propose to only retry if we have a known retryable error code.

(note: I considered moving this upstream to is-retry-allowed but I think it's a got concern first and foremost. It's weird we have a default true and a whitelist in that module.)

(related: nock/nock#898 I've been pushing for this for nock because it's really annoying when developing, but I'm starting to think got should solve this. I'm not 100% yet)

[sindresorhus]

I would be ok with that, as we already have a good whitelist and blacklist, so the error.code check would only apply to unknown errors.

@reconbot Can you think of any downside with doing this?

@floatdrop @alextes @lukechilds Thoughts?

[lukechilds]

I agree, retries should be whitelist only.

There may be multiple proprietary errors along the lines of API_LIMIT_REACHED which should obviously not be retried.

Edit: Oh wait, those are Node.js errors right? Not HTTP errors. So moot point about API limit responses, but still agree it should be whitelist only.