khatru: only kill connection once.

khatru/handlers.go

@@ -108,7 +108,9 @@ func (rl *Relay) HandleWebsocket(w http.ResponseWriter, r *http.Request) {
 		),
 	)
 
+	killOnce := sync.Once{}
 	kill := func() {
+		killOnce.Do(func() {
 			if nil != rl.OnDisconnect {
 				rl.OnDisconnect(ctx)
 			}
@@ -119,6 +121,7 @@ func (rl *Relay) HandleWebsocket(w http.ResponseWriter, r *http.Request) {
 			ws.conn.Close()
 
 			rl.removeClientAndListeners(ws)
+		})
 	}
 
 	go func() {