code: function formatError(e) {
  		var s = typeof e === 'object' && e !== null && (e.stack || e.message) ? e.stack || e.message : formatObject(e);
  		return e instanceof Error ? s : s + ' (WARNING: non-Error used)';
  	}
docs: Format an error into a string.  If e is an Error and has a stack property,
  it's returned.  Otherwise, e is formatted using formatObject, with a
  warning added about e not being a proper Error.
  @param {*} e
  @returns {String} formatted string, suitable for output to developers