[FIXED] Interface conversion bug for ipQueues in monitor which would cause panics. (#4477)

Signed-off-by: Derek Collison <derek@nats.io>

server/monitor.go

@@ -1120,14 +1120,17 @@ func (s *Server) HandleIPQueuesz(w http.ResponseWriter, r *http.Request) {
 
 	queues := map[string]monitorIPQueue{}
 
-	s.ipQueues.Range(func(k, v interface{}) bool {
+	s.ipQueues.Range(func(k, v any) bool {
+		var pending, inProgress int
 		name := k.(string)
-		queue := v.(interface {
+		queue, ok := v.(interface {
 			len() int
-			inProgress() uint64
+			inProgress() int64
 		})
-		pending := queue.len()
-		inProgress := int(queue.inProgress())
+		if ok {
+			pending = queue.len()
+			inProgress = int(queue.inProgress())
+		}
 		if !all && (pending == 0 && inProgress == 0) {
 			return true
 		} else if qfilter != _EMPTY_ && !strings.Contains(name, qfilter) {

server/monitor_test.go

@@ -4981,3 +4981,22 @@ func TestHealthzStatusUnavailable(t *testing.T) {
 
 	checkHealthzEndpoint(t, s.MonitorAddr().String(), http.StatusServiceUnavailable, "unavailable")
 }
+
+// When we converted ipq to use generics we still were using sync.Map. Currently you can not convert
+// interface{} or any to a generic parameterized type. So this stopped working and panics.
+func TestIpqzWithGenerics(t *testing.T) {
+	opts := DefaultMonitorOptions()
+	opts.JetStream = true
+
+	s := RunServer(opts)
+	defer s.Shutdown()
+
+	url := fmt.Sprintf("http://%s/ipqueuesz?all=1", s.MonitorAddr().String())
+	body := readBody(t, url)
+	require_True(t, len(body) > 0)
+
+	queues := map[string]*monitorIPQueue{}
+	require_NoError(t, json.Unmarshal(body, &queues))
+	require_True(t, len(queues) >= 4)
+	require_True(t, queues["SendQ"] != nil)
+}