ShowNonBusiness="false" Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index

I seem to have found a bug in the DayPilot ASP.NET control. I believe that I am having the same issue described here:
https://forums.daypilot.org/Topic.aspx/2460/business-hours-7-days-a-week-weekends-crash

ASP.NET WebForms and the DayPilot control.
Set ShowNonBusiness="false"
The current day is set to Saturday.
If I compile with ShowNonBusiness="true" and then change it to false manually, the control seems to work again.

Here is the error that I am receiving:
Server Error in '/' Application.

Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: index