Readonly Grid

Hi Guys

I tried to create a readonly grid where i have one column with document download link . I did null handling for that when we have a document i should be able to see the download icon with link if we dont have any document i should be able to see the text message stating no documents .When i tried to open the component configuration for the read only grid i am encountering the error. Please find the image which i  attached .Can someone help me this error what exactly.

Thanks in advance