Requesting a deleted image/asset throws a 500 error

If you request an image or asset that has been deleted, then Preside returns a 500 server error (and logs the error). This also occurs if you request a non-existent asset ID, but with a derivative appended to the URL.

This should return a 404 not found error. This will not only be more correct, but it will also stop the system logging the server error, which will lighten the logs and save the cycles needed to process the error...