Method prepareError_

third_party/subscriptions-project/config.js:550–558

* Modifies an error before reporting, such as to add metadata. * @param {!Error} error * @private

(error)

   * @private
   */
  prepareError_(error) {
    if (this.suffix_) {
      if (!error.message) {
        error.message = this.suffix_;
      } else if (error.message.indexOf(this.suffix_) === -1) {
        error.message = this.suffix_;
      }
    }
  }

  /**
   * Creates an error.