Thanks again for reporting the exception.
However you can try the latest internal build from the site released a week ago.
The release note can be found here:
Additionally, If you are still facing the exception with the above mentioned build then you can send me the exception message along with the class that is causing it which I will use to investigate the problem and possibly can you the fix through a private build (In that regard you have to open a support ticket).
the Telerik team
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