I'm getting the below error when focusing out of the "RadDateTimePicker" with the following configuration.

Code in the aspx page:

<telerik:RadDateTimePicker runat="server" ID="TlrkDateTimeEdit"
DateInput-DateFormat="g" DateInput-DisplayDateFormat="g"
DatePopupButton-Visible="false" TimePopupButton-Visible="false"
PopupDirection="BottomLeft" ShowPopupOnFocus="true">
</telerik:RadDateTimePicker>

Script error in browser console:
"Cannot read properties of null (reading 'focus')    at Telerik.Web.UI.Calendar.Popup._raiseClosed"

In version R3 2019 (2019.3.917), the following issue is observed with various date pickers: 

Reproduction code and steps:

<telerik:RadDateTimePicker RenderMode="Lightweight" ID="RadDateTimePicker1"  runat="server" >
</telerik:RadDateTimePicker>

1) open date picker, 
2) click on the month/year to open the MonthYearFastNavigation
3) Click Ok or Cancel

Expected: date selected
Actual: JavaScript error: Uncaught TypeError: Cannot read property '_popupButton' of null