fix: prevent OnPerformanceTickData from sending data on null (#614)

If something causes an exception it's possible that the profiler never allocates data. in these cases, there is no point in sending data outside of MLAPI

Author: kvassall-unity

com.unity.multiplayer.mlapi/Runtime/Core/NetworkManager.cs

@@ -652,11 +652,7 @@ public void NetworkUpdate(NetworkUpdateStage updateStage)
 
         private void OnNetworkEarlyUpdate()
         {
-            PerformanceDataManager.BeginNewTick();
-            if (NetworkConfig.NetworkTransport is ITransportProfilerData profileTransport)
-            {
-                profileTransport.BeginNewTick();
-            }
+            ProfilerBeginTick();
 
             if (IsListening)
             {
@@ -760,13 +756,7 @@ private void OnNetworkPreUpdate()
                 }
             }
 
-            if (NetworkConfig.NetworkTransport is ITransportProfilerData profileTransport)
-            {
-                var transportProfilerData = profileTransport.GetTransportProfilerData();
-                PerformanceDataManager.AddTransportData(transportProfilerData);
-            }
-
-            OnPerformanceDataEvent?.Invoke(PerformanceDataManager.GetData());
+            NotifyProfilerListeners();
         }
 
         internal void UpdateNetworkTime(ulong clientId, float netTime, float receiveTime, bool warp = false)
@@ -1495,5 +1485,37 @@ internal void HandleApproval(ulong clientId, bool createPlayerObject, ulong? pla
                 NetworkConfig.NetworkTransport.DisconnectRemoteClient(clientId);
             }
         }
+
+        private void ProfilerBeginTick()
+        {
+            PerformanceDataManager.BeginNewTick();
+            if (NetworkConfig.NetworkTransport is ITransportProfilerData profileTransport)
+            {
+                profileTransport.BeginNewTick();
+            }
+        }
+
+        private void NotifyProfilerListeners()
+        {
+            var data = PerformanceDataManager.GetData();
+            var eventHandler = OnPerformanceDataEvent;
+            if (eventHandler != null)
+            {
+                if (data != null)
+                {
+                    if (NetworkConfig.NetworkTransport is ITransportProfilerData profileTransport)
+                    {
+                        var transportProfilerData = profileTransport.GetTransportProfilerData();
+                        PerformanceDataManager.AddTransportData(transportProfilerData);
+                    }
+
+                    eventHandler.Invoke(data);
+                }
+                else
+                {
+                    NetworkLog.LogWarning("No data available. Did you forget to call PerformanceDataManager.BeginNewTick() first?");
+                }
+            }
+        }
     }
 }