cubicweb-timesheet #1729910 activity_calendar view crashes if calendar misses some daytypes [validation pending]

The incriminated code is:

dtypes = resource.get_day_types(firstday, lastday)
# ...
for date_, ... in resource.iter_activities(firstday, lastday):
    dtype = self._cw.entity_from_eid(dtypes[date_][0])

dtypes[date_] may throw a KeyError since date_ is not necessarily defined in the resource's calendar (e.g. a Calendar starting in the middle of the month).

done in0.6.0
load left0.000
closed by#f27576b93324 [views] do not crash if dtypes misses a date (closes #1729910)