There is a crash that occurs at: https://secure.phabricator.com/diffusion/P/browse/master/src/applications/phragment/controller/PhragmentZIPController.php;1d9bf6f82b30817ed4fc7300d6f1469ea4770e05$90
This occurs because the query returns a null file (presumably because it's a file that can not be seen due to policies) and calling loadFileData() on a null value fails. This should check to see if the file is null, and if so, just skip over it if the user can't access it.
This scenario is only possible for fragments created before policies are introduced into Phragment.