message: add test for invalid param
diff: @@ -33,4 +33,8 @@ describe('W3C dates strings ', () => {
  expect(date1.getMinutes()).toBe(date.getMinutes());
  expect(date.getTimezoneOffset()).toBe(date.getTimezoneOffset());
  });
  +
  + it('throws on invalid argument type', () => {
  + expect(() => getW3CDateString({ byaka: 'buka' })).toThrow(TypeError);
  + });
  });
  