Steps to reproduce:
1. Control Panel > Documents & Media
2. Drag/Drop a file from your computer into the portlet
4. Inspect the app-view-entry element. It should have a class "null"
Note: When attempting to inspect the app-view-entry element, it will help to understand its structure:
(This was the structure I saw from a fresh bundle on 6.2.x)
> div.app-view-entry (has the null class)