Helper baseclass sets `this.opts` in `setConfig`, not `this.config`?

[tfh-cri]

I was trying to work out why the documented details around Scenario(...).config('SomeHelper', {...}) weren't working for me, and as
far as I can tell, the default base class implementation of _setConfig is actually setting this.opts rather than this.config (which I presume is the correct version, since it's mentioned both in the docs and is assigned initially in the constructor).

https://github.com/codeceptjs/helper/blob/master/helper.js#L48

Unless I'm misunderstanding something here, I'd expect _setConfig to also be updating config member?