fix: return a grpc error when discard failed

Signed-off-by: ningmingxiao <ning.mingxiao@zte.com.cn>

Author: ningmingxiao

channel.go

@@ -125,9 +125,8 @@ func (ch *channel) recv() (messageHeader, []byte, error) {
 
 	if mh.Length > uint32(messageLengthMax) {
 		if _, err := ch.br.Discard(int(mh.Length)); err != nil {
-			return mh, nil, fmt.Errorf("failed to discard after receiving oversized message: %w", err)
+			return mh, nil, status.Errorf(codes.ResourceExhausted, "failed to discard after receiving oversized message: %s (message length %v maximum message size %v)", err.Error(), mh.Length, messageLengthMax)
 		}
-
 		return mh, nil, status.Errorf(codes.ResourceExhausted, "message length %v exceed maximum message size of %v", mh.Length, messageLengthMax)
 	}