Monolithic blob upload swallows chunk upload errors

[coryodaniel]

In lib/oci/plug/handler.ex (monolithic POST dispatch), the result of Registry.upload_blob_chunk is pattern matched but errors are silently ignored — the code falls through to complete_blob_upload regardless.

case Registry.upload_blob_chunk(...) do
  {:ok, _, _} -> :ok
  err -> err  # this result is discarded
end

case Registry.complete_blob_upload(...) do
  ...
end

The err return from the first case is never used — execution always continues to complete_blob_upload. If the chunk upload fails, the complete will likely also fail, but with a misleading error.

Should propagate the error and return an appropriate HTTP response instead of continuing.