Update websocket_client.go

stream/websocket_client.go

@@ -140,6 +140,8 @@ type sub_cmd struct {
 }
 
 func (w *Receiver) subscribe() error {
+	w.c.Lock()
+	defer w.c.Unlock()
 	return w.c.c.WriteJSON(sub_cmd{Method: "topic_subscribe", Params: []string{w.topic}})
 }
 
@@ -164,8 +166,8 @@ func (w *Receiver) OnPatchRaw(seq int, diffs gjson.RawMessage) error {
 }
 
 func (w *Receiver) Close() {
-	w.c.c.WriteJSON(sub_cmd{Method: "topic_unsubscribe", Params: []string{w.topic}})
 	w.c.Lock()
 	defer w.c.Unlock()
+	w.c.c.WriteJSON(sub_cmd{Method: "topic_unsubscribe", Params: []string{w.topic}})
 	delete(w.c.Streams, w.topic)
 }