don't display a broken thumbnail image if a thumbnail is not available

cms/djangoapps/contentstore/views.py

@@ -848,9 +848,9 @@ def asset_index(request, org, course, name):
         display_info['url'] = StaticContent.get_url_path_from_location(asset_location)
         
         # note, due to the schema change we may not have a 'thumbnail_location' in the result set
-        thumbnail_location = Location(asset.get('thumbnail_location', None))
-
-        display_info['thumb_url'] = StaticContent.get_url_path_from_location(thumbnail_location)
+        _thumbnail_location = asset.get('thumbnail_location', None)
+        thumbnail_location = Location(_thumbnail_location) if _thumbnail_location is not None else None
+        display_info['thumb_url'] = StaticContent.get_url_path_from_location(thumbnail_location) if thumbnail_location is not None else None
         
         asset_display.append(display_info)
 

cms/templates/asset_index.html

@@ -26,7 +26,11 @@
           % for asset in assets:
             <tr>
               <td class="thumb-col">
-                <div class="thumb"><img src="${asset['thumb_url']}"></div>
+                <div class="thumb">
+                  % if asset['thumb_url'] is not None:
+                  <img src="${asset['thumb_url']}">
+                  % endif
+                </div>
               </td>
               <td class="name-col">
                 <a href="${asset['url']}" class="filename">${asset['displayname']}</a>