title: UrlFetchApp.fetch() skip on empty cell
body: <p>I've written a script that gets an image url from a cell in Google Sheets and adds that image to a template in Google Docs. However, when the cell is empty, the script crashes:</p>
  <pre><code>var beforePhoto1 = UrlFetchApp.fetch(row[14]).getBlob();
  </code></pre>
  <p>Really new to programming and would appreciate anyones help as to how to prevent the above code from crashing in the event a cell is empty</p>