fix socket

server/src/rpc.rs

@@ -156,7 +156,7 @@ pub fn receive(data: Vec<u8>, db: &Db, _client: &mut MnmlWs, begin: Instant, acc
         },
         Err(e) => {
             info!("{:?}", e);
-            Err(err_msg("invalid message"))
+            Err(format_err!("invalid message data={:?}", data))
         },
     }
 }