owncloud/core — pull request #12546 by oparoz (2014-12-02 13:21:29+00:00)
Title: Send the mime icon if we can't generate a preview

Sending an invalid OC_Image instance can lead to all sorts of unwanted side effects with 3rd party apps.
The first step to fix this would be to send the mime icon.
Later on we could maybe generate a broken image to send back, to indicate that we were unsuccessful in generating a preview.