Method assertString

src/utils/log.js:433–439

* Throws an error if the first argument isn't a string. The string can * be empty. * * For more details see `assert`. * * @param {*} shouldBeString * @param {!Array|string=} opt_message The assertion message * @return {string} The string value. Can be an empty string. * @clos

(shouldBeString, opt_message)

   * @closurePrimitive {asserts.matchesReturn}
   */
  assertString(shouldBeString, opt_message) {
    return assertions.assertString(
      this.boundAssertFn_,
      shouldBeString,
      opt_message
    );
  }

  /**
   * Throws an error if the first argument isn't a number. The allowed values