From a61d8f7bd762efae4ecd8de53ff34c07989bf796 Mon Sep 17 00:00:00 2001
From: Quinn Slack <qslack@qslack.com>
Date: Sun, 22 Jan 2017 15:45:18 -0800
Subject: [PATCH] warn when marshaling invalid Response

---
 jsonrpc2.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/jsonrpc2.go b/jsonrpc2.go
index 9ec1297..c7724ac 100644
--- a/jsonrpc2.go
+++ b/jsonrpc2.go
@@ -132,6 +132,9 @@ func (r *Response) MarshalJSON() ([]byte, error) {
 	if r == nil {
 		return nil, errors.New("can't marshal nil *jsonrpc2.Response")
 	}
+	if (r.Result == nil || len(*r.Result) == 0) && r.Error == nil {
+		return nil, errors.New("can't marshal *jsonrpc2.Response (must have result or error)")
+	}
 	b, err := json.Marshal(*r)
 	if err != nil {
 		return nil, err