It seems to be an error in the Module's recently added iterator feature, it's definitely worth filing a bug. I found that if I leave off the last argument to sunrise, I get an answer for that date.
in reply to Astro::Sunrise error
That seems to be about three minutes off for both sunrise and sunset from what I get at this page:
Assuming that site is correct, it may still be close enough for your purposes.
Update: corrected some numbers above.