While StatusCode can already be parsed as a response,
it's not always easy to propagate the correct Ok() signature
in a method that only returns errors.
Throw the error variant is trivial, but verbose so an helper method
error_response(status_code, error_message) can be helpful to keep
code easy to read and maintain.
Expected use:
if ... {
return error_response(StatusCode::..., "...");
}