function _smallest(x, y) {
    try {
      return smaller(x, y) ? x : y;
    } catch (err) {
      throw improveErrorMessage(err, 'min', y);
    }
  }
Return the smallest of two values
@param {*} x
@param {*} y
@returns {*} Returns x when x is smallest, or y when y is smallest
@private