Upd: we've found the bug, will fix with the next release.
There's a bug on Weekplan's Calendar view. It doesn't happen to all, but, apparently, quite some users are affected.
Some users wrote in their crash reports that they just click on the Calendar view and it fails. But, most probably there are some other prerequisites, as we do the same - just click everywhere on the calendar view - and it doesn't fail. Would be great if anyone could give us those steps.
If somehow you know the steps, please, tell us at firstname.lastname@example.org - that would be a very great help to us! Thank you!