         return stringify(obj)
 
     save_blob: (blob, to_db) =>
+        if not @blobs?
+            return
         id = misc.uuidsha1(blob)
         if @blobs[id]
             return id

                        id   : id
                        blob : null
                cb: (err, resp) =>
                    if @state == 'closed'
                        return
                    delete @blobs_pending[id]
                    if err

        return id

    load_blob: (id) =>
        if not @blobs?
            return
        blob = @blobs[id]
        if blob?
            return blob
