Getting errors referring to line 405 with a calendar feed that was working fine. I am guessing that an event that is now within range (set to show 3 events from today to a month from now) has some entity that's causing trouble. On a hunch I updated the event shown in the second error, changing the '&' in the location (New Yorker Hotel, 481 8th Avenue &...) to 'and'. However despite deleting and re-adding the widget, replacing the feed, etc.. the previous location still shows.... perhaps the feed is still cached locally?
The test page shows a Kalendas widget instance with a non-problematic calendar first.
The xml feed for the problematic calendar is here: