code: func adaptGrpcErr(h func(*router.Context) error) router.Handler {
  	return func(ctx *router.Context) {
  		err := grpcutil.GRPCifyAndLogErr(ctx.Context, h(ctx))
  		if code := grpc.Code(err); code != codes.OK {
  			http.Error(ctx.Writer, grpc.ErrorDesc(err), grpcutil.CodeStatus(code))
  		}
  	}
  }
docs: // adaptGrpcErr knows how to convert gRPC-style errors to ugly looking HTTP
  // error pages with appropriate HTTP status codes.
  //
  // Recognizes either real gRPC errors (produced with status.Errorf) or
  // grpc-tagged errors produced via grpcutil.