This is intentional and needs commenting. If the configuration for this setting has the passed option key in the `options` array, this is a valid option. If this setting has no options configuration (ie. empty or undefined), we assume the partner/'configurer' is allowing **any** given options for this setting (like `pictureSizes`), so the option **is** valid.

ACTION:

1. Document/comment this.
2. Make sure we have unit test coverage to prove this is working