it('fallsback and warns on invalid Intl.DateTimeFormat options', () => {
                expect(formatDate(0, {year: 'invalid'})).toBe(String(new Date(0)));
                expect(consoleError.calls.length).toBe(1);
                expect(consoleError.calls[0].arguments[0]).toContain(
                    '[Intl Format] Error formatting date.\nRangeError'