I agree with cdiebolt. While there was no such date in England's dating system at the time, it's a perfectly valid date in the Gregorian calendar, and corresponds to various dates in various countries' national systems.
So the function DOES do what I expected, hence it runs perfectly. "Perfect" is in the of the beholder, so not a word to be used in a specification - unless itself specified for the occasion. Please make the possible answers unambiguous in future - and scope the conditions precisely too.
I wonder if anyone has created a nation-sensitive historic date system in which Date('1752-09-02') + 1 would give the correct result depending on country. e.g. '1752-09-13' in England (and I think the rest of the UK), and '1752-09-03' in The Netherlands? It would be hard to do; you couldn't use ISO country codes to indicate locale, as some no longer exist and others (e.g. Belgium) were parts of multiple other countries at the time.