When cliking on the "Delete attachment" link, and opening the URL
in a new tab, the `DELETE /attachements/:id` will become
`GET /attachments/:id` – which will cause the `show` action to be
routed with an html format (instead of JS).
In that case, we don't want to throw an error at the user face.
Instead simply re-render the dossier page (if any).
Fix a long-standing error in Sentry.
b748e9773f