fix: Exception with disabled GameObjects and NetworkTransforms

Author: EmandM

com.unity.netcode.gameobjects/Runtime/Messaging/Messages/NetworkTransformMessage.cs

@@ -71,8 +71,21 @@ public bool Deserialize(FastBufferReader reader, ref NetworkContext context, int
             if (isSpawnedLocally)
             {
                 networkObject = networkManager.SpawnManager.SpawnedObjects[networkObjectId];
+                if (networkObject.ChildNetworkBehaviours.Count <= networkBehaviourId || networkObject.ChildNetworkBehaviours[networkBehaviourId] == null)
+                {
+                    Debug.LogError($"[{nameof(NetworkTransformMessage)}][Invalid][length] Targeted {nameof(NetworkTransform)}, {nameof(NetworkBehaviour.NetworkBehaviourId)} ({networkBehaviourId}), does not exist! Make sure you are not spawning {nameof(NetworkObject)}s with disabled {nameof(GameObject)}s that have {nameof(NetworkBehaviour)} components on them.");
+                    return false;
+                }
+
                 // Get the target NetworkTransform
-                NetworkTransform = networkObject.ChildNetworkBehaviours[networkBehaviourId] as NetworkTransform;
+                var transform = networkObject.ChildNetworkBehaviours[networkBehaviourId] as NetworkTransform;
+                if (transform == null)
+                {
+                    Debug.LogError($"[{nameof(NetworkTransformMessage)}][Invalid][cast] Targeted {nameof(NetworkTransform)}, {nameof(NetworkBehaviour.NetworkBehaviourId)} ({networkBehaviourId}), does not exist! Make sure you are not spawning {nameof(NetworkObject)}s with disabled {nameof(GameObject)}s that have {nameof(NetworkBehaviour)} components on them.");
+                    return false;
+                }
+
+                NetworkTransform = transform;
                 isServerAuthoritative = NetworkTransform.IsServerAuthoritative();
                 ownerAuthoritativeServerSide = !isServerAuthoritative && networkManager.IsServer;
 
@@ -81,8 +94,8 @@ public bool Deserialize(FastBufferReader reader, ref NetworkContext context, int
             }
             else
             {
-                // Deserialize the state
-                reader.ReadNetworkSerializableInPlace(ref State);
+                Debug.LogError($"[{nameof(NetworkTransformMessage)}][Invalid] Target NetworkObject does not exist!");
+                return false;
             }
 
             unsafe

com.unity.netcode.gameobjects/Tests/Runtime/NetworkTransform/NetworkTransformErrorTests.cs

@@ -0,0 +1,120 @@
+using System.Collections;
+using Unity.Netcode.Components;
+using Unity.Netcode.TestHelpers.Runtime;
+using UnityEngine;
+using UnityEngine.TestTools;
+
+
+namespace Unity.Netcode.RuntimeTests
+{
+    internal class NetworkTransformErrorTests : NetcodeIntegrationTest
+    {
+        protected override int NumberOfClients => 1;
+
+        private GameObject m_ServerPrefab;
+        private GameObject m_ClientPrefab;
+
+        private HostAndClientPrefabHandler m_HostAndClientPrefabHandler;
+
+        public class EmptyNetworkBehaviour : NetworkBehaviour { }
+
+        /// <summary>
+        /// PrefabHandler that tracks and separates the client GameObject from the host GameObject.
+        /// Allows independent management of client and host game world while still instantiating NetworkObjects as expected.
+        /// </summary>
+        private class HostAndClientPrefabHandler : INetworkPrefabInstanceHandler
+        {
+            private readonly GameObject m_HostPrefab;
+            private readonly GameObject m_ClientPrefab;
+
+            public HostAndClientPrefabHandler(GameObject hostPrefab, GameObject clientPrefab)
+            {
+                m_HostPrefab = hostPrefab;
+                m_ClientPrefab = clientPrefab;
+            }
+
+            public NetworkObject Instantiate(ulong ownerClientId, Vector3 position, Quaternion rotation)
+            {
+                // Owner clientID
+                if (ownerClientId == 0)
+                {
+                    return Object.Instantiate(m_ClientPrefab).GetComponent<NetworkObject>();
+                }
+                return Object.Instantiate(m_HostPrefab).GetComponent<NetworkObject>();
+            }
+
+            public void Destroy(NetworkObject networkObject)
+            {
+                Object.Destroy(networkObject.gameObject);
+            }
+
+            public void Register(NetworkManager networkManager)
+            {
+                networkManager.PrefabHandler.AddHandler(m_HostPrefab, this);
+            }
+        }
+
+        /// <summary>
+        /// Creates a GameObject and sets the transform parent to the given transform
+        /// Adds a component of the given type to the GameObject
+        /// </summary>
+        private static void AddChildToNetworkObject<T>(Transform transform) where T : Component
+        {
+            var gameObj = new GameObject();
+            gameObj.transform.parent = transform;
+            gameObj.AddComponent<T>();
+        }
+
+        protected override void OnServerAndClientsCreated()
+        {
+            // Full non-disabled GameObjects prefab on server side
+            m_ServerPrefab = CreateNetworkObjectPrefab("ServerPrefab");
+            AddChildToNetworkObject<EmptyNetworkBehaviour>(m_ServerPrefab.transform);
+            AddChildToNetworkObject<EmptyNetworkBehaviour>(m_ServerPrefab.transform);
+            AddChildToNetworkObject<NetworkTransform>(m_ServerPrefab.transform);
+
+            // Mock disabled GameObjects prefab on client side
+            m_ClientPrefab = CreateNetworkObjectPrefab("ClientPrefab");
+            AddChildToNetworkObject<NetworkTransform>(m_ClientPrefab.transform);
+
+            // Create and register prefab handler to handle server and client versions of prefabs
+            m_HostAndClientPrefabHandler = new HostAndClientPrefabHandler(m_ServerPrefab, m_ClientPrefab);
+            m_HostAndClientPrefabHandler.Register(m_ServerNetworkManager);
+            foreach (var client in m_ClientNetworkManagers)
+            {
+                m_HostAndClientPrefabHandler.Register(client);
+            }
+
+            base.OnServerAndClientsCreated();
+        }
+
+
+        [UnityTest]
+        public IEnumerator DisabledGameObjectErrorTest()
+        {
+            var instance = SpawnObject(m_ServerPrefab, m_ServerNetworkManager);
+            var networkObjectInstance = instance.GetComponent<NetworkObject>();
+
+            yield return WaitForConditionOrTimeOut(() => ObjectSpawnedOnAllClients(networkObjectInstance.NetworkObjectId));
+            AssertOnTimeout("Timed out waiting for object to spawn!");
+
+            LogAssert.Expect(LogType.Error, "[Netcode] NetworkBehaviour index 3 was out of bounds for ClientPrefab(Clone). NetworkBehaviours must be the same, and in the same order, between server and client.");
+            LogAssert.Expect(LogType.Error, "[NetworkTransformMessage][Invalid][length] Targeted NetworkTransform, NetworkBehaviourId (3), does not exist! Make sure you are not spawning NetworkObjects with disabled GameObjects that have NetworkBehaviour components on them.");
+
+            yield return new WaitForSeconds(0.3f);
+        }
+
+        private bool ObjectSpawnedOnAllClients(ulong networkObjectId)
+        {
+            foreach (var client in m_ClientNetworkManagers)
+            {
+                if (!client.SpawnManager.SpawnedObjects.ContainsKey(networkObjectId))
+                {
+                    return false;
+                }
+            }
+            return true;
+        }
+    }
+
+}