Using a hard-coded image source here is a little inconsistent. This is essentially an attachment placeholder, and we already have a spritesheet for those in `style/icons/attachments.png`. Using the existing spritesheet will be more performant.

It would be better to implement this with an `image-corrupted` (or similar) CSS class. This would let us write tests that don't contain presentation details, which in turn would promote maintainability.