message: Fix handling of non-200 OK responses with C++REST
diff: @@ -241,7 +241,7 @@ private:
  // handle non-OK responses:
  void handle_error(http::http_response r)
  {
  - if (r.status_code() == http::status_codes::OK)
  + if (r.status_code() >= 200 && r.status_code() < 300)
  return; // not an error
  int status_code = r.status_code();
  