Downloading a CID that is unknown to the network would wait for the blockexchange to try to get the data. However, a subsequent API call, eg upload for that CID, or a blockexchange timeout would cause the dagger node to crash, due to an attempt to complete a future that had already been completed.
We were able to narrow this down to an attempt to call `resp.finish()` when the download block had already returned an `RestApiResponse` (and never sent any chunks to the response from the libp2p stream).
Change the HTTP response code for an unknown cid from 400 to 404.
Fix spelling mistake “cunk”.
Co-authored-by: Michael Bradley <michaelsbradleyjr@gmail.com>
Co-authored-by: Michael Bradley <michaelsbradleyjr@gmail.com>