Mini-calender outside calender produces errors #71
Description
Expected behavior:
When using mini-calender outside of the scheduler it should not produce any exception when selecting a date via mini-calender and should lead to correct switch of day in scheduler.
Current behavior:
Selecting specific dates in mini-calender can produce a type-error "Cannot read properties of undefined (reading 'cells')".
When selecting one of this dates and changing to month before by arrow back button in mini-calender it produces the exception. Now selecting any day of the opened month gets impossible until changing to another month and day.
How to reproduce:
Open related example Mini calendar outside the scheduler
Go to "day"-tab in scheduler, select October 10th 2022 for example and navigate back by arrow back button in mini-calender.
Can also be reproduces by other dates like May 9th 2022, March 14th 2022 and so on. Mostly second monday of a month.