I missed this at first, but now that I'm looking at it more intently I don't think errors belong in the model. Models are for the domain-y data contained within the response, the errors should just live on the response object itself. Also if any errors are present in the response a `Cb::ApiResponseError` is immediately thrown, carrying them around like this accomplishes little unless you catch the error first, discard it, and for some reason need to reference the text version from the API later.