Fix blank screen in Spreadsheet Editor when 'thumbnail' column is included

Spreadsheet Editor shows a blank page when the Thumbnail column has to be rendered.
How to reproduce:

• navigate to a folder and include the Thumbnail column in the listing
• open the Spreadsheet Editor

Expected result: the Spreadsheet Editor opens and renders all the rows and columns
Actual result: The Spreadsheet Editor stays blank

Important notes:

• this is a regression introduced by 10.10-HF21 (NXP-27918)
• the user reports that when this issue is fixed it raised another error the some documents don't have a thumbnail, errors are reported in the browser's console