This block isn't strictly necessary—we can refactor and discuss—but it's been useful in two commons cases. In debug mode when the image can't be found, this substitutes a (in our case) 1 pixel gray image and attaches the path of the intended-but-missing file along with a flag. The template (we have a single shared generic image display template) uses the defined `version` dimensions to set the height and width `<img>` attributes resulting in a placeholder grey box appearing exactly how the real image would appear and thus not breaking layouts. A little JavaScript warns in the console.

```
{% if file.missing_file %}
  <script>window.console && console.warn("broken image: {{ file.actual_path }}");</script>
{% endif %}
````
This has been really helpful when running on a development database (incorrect image paths), when using a development S3 bucket (no actual images) and when working without Internet (like on a train). We also use a `USE_REMOTE_FILE_STORAGE` setting for "train development" that short circuits having to wait for the `self.field.storage.exists()` timeout.