I get the same error when I try to $cal->find() a month that has an event spanning into it:
Error Cannot break/continue 1 level (line 340
Events that continue beyond the loaded timespan are fine.
That line goes as follows, and, judging from the comment, I don't want that functionality anyways, so I commented it out. Now my output looks good, although I'm not very comfortable with messing with the code...
// filter out events that started before the requested time
// these will be multi-day events that span into the requested time
if($from && $a->from < $from) continue;
The point in my code that throws the error:
$items = $Calendar->find("from=$year-$month-1, to=$year-$month-$numdays, sort=date");
Otherwise everything is going super swell, thanks a lot for ProcessWire!