I noticed that an hour ago and have been working on fixing it. The proxy just doesn't like data being return - the image is written out with a header - and probably rightly so too since it is a common method to attack servers... I am still working an a patch which involves switching it out with static content. It does still work though, the data is saved when I receive the request and the error is return when its parses my response. I think we have just found a potential minor vulnerability - when I wrote the code I tested in the editor, just checked again to be sure. The editor does not proxy the image.