code: function normalizeTypeDescriptors(types) {
    let [requestType, successType, failureType] = types;
  
    if (typeof requestType === 'string' || typeof requestType === 'symbol') {
      requestType = { type: requestType };
    }
  
    if (typeof successType === 'string' || typeof successType === 'symbol') {
      successType = { type: successType };
    }
    successType = {
      payload: (action, state, res) => getJSON(res),
      ...successType
    };
  
    if (typeof failureType === 'string' || typeof failureType === 'symbol') {
      failureType = { type: failureType };
    }
    failureType = {
      payload: (action, state, res) =>
        getJSON(res).then(json => new ApiError(res.status, res.statusText, json)),
      ...failureType
    };
  
    return [requestType, successType, failureType];
  }
docs: Blow up string or symbol types into full-fledged type descriptors,
  and add defaults
  
  @function normalizeTypeDescriptors
  @access private
  @param {array} types - The [RSAA].types from a validated RSAA
  @returns {array}