Undefined index: file in media_admin_thumbnails()

Clicking on "Content -> Media" from administrator interface, if no file exists in your media folder, you can see the errors:
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- Notice: Undefined index: file in media_admin_thumbnails() (line 167 of /my/path/sites/all/modules/media/includes/media.admin.inc).
- Warning: array_keys() expects parameter 1 to be array, null given in media_admin_thumbnails() (line 167 of /my/path/sites/all/modules/media/includes/media.admin.inc).
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To solve this problem, in the above file I
- add at 166: if (!empty($result)){
- and close it at 187: }

It seems to work: I hope it is correct.