Consider using a Sum Type instead of throwing on Error

[sibelius]

Based on this https://gist.github.com/jcemer/f4bef63864f73307df44d3ddc2383214

by @jcemer

type ResultsResponse =
  | Ok<T>
  | Error

this will make the user always check the response error

[sibelius]

related to

https://flow.org/en/docs/types/unions/#toc-unions-refinements
https://flow.org/blog/2015/07/03/Disjoint-Unions/