fix(ws): wrongly sending nil as error when write on close fails

js/modules/k6/ws/ws.go

@@ -432,14 +432,13 @@ func (s *Socket) closeConnection(code int) error {
 	s.shutdownOnce.Do(func() {
 		rt := common.GetRuntime(s.ctx)
 
-		writeErr := s.conn.WriteControl(websocket.CloseMessage,
+		err = s.conn.WriteControl(websocket.CloseMessage,
 			websocket.FormatCloseMessage(code, ""),
 			time.Now().Add(writeWait),
 		)
-		if writeErr != nil {
+		if err != nil {
 			// Just call the handler, we'll try to close the connection anyway
 			s.handleEvent("error", rt.ToValue(err))
-			err = writeErr
 		}
 
 		// trigger `close` event when the client closes the connection

js/modules/k6/ws/ws_test.go

@@ -354,6 +354,35 @@ func TestErrors(t *testing.T) {
 		assert.NoError(t, err)
 		assertSessionMetricsEmitted(t, stats.GetBufferedSamples(samples), "", sr("WSBIN_URL/ws-echo"), 101, "")
 	})
+
+	t.Run("error on close", func(t *testing.T) {
+		_, err := common.RunString(rt, sr(`
+		var closed = false;
+		let res = ws.connect("WSBIN_URL/ws-close", function(socket){
+			socket.on('open', function open() {
+				socket.setInterval(function timeout() {
+				  socket.ping();
+				}, 1000);
+			});
+
+			socket.on("ping", function() {
+				socket.close();
+			});
+
+			socket.on("error", function(errorEvent) {
+				if (errorEvent == null) {
+					throw new Error(JSON.stringify(errorEvent));
+				}
+				if (!closed) {
+					closed = true;
+				    socket.close();
+				}
+			});
+		});
+		`))
+		assert.NoError(t, err)
+		assertSessionMetricsEmitted(t, stats.GetBufferedSamples(samples), "", sr("WSBIN_URL/ws-close"), 101, "")
+	})
 }
 
 func TestSystemTags(t *testing.T) {