fix: Avoid throwing exception when using NetworkList without a NetworkManager

Author: EmandM

com.unity.netcode.gameobjects/CHANGELOG.md

@@ -13,6 +13,7 @@ Additional documentation and release notes are available at [Multiplayer Documen
 
 ### Fixed
 
+- Fixed `NullReferenceException` on `NetworkList` when used without a NetworkManager in scene. (#3503)
 - Fixed issue where `NetworkClient` could persist some settings if re-using the same `NetworkManager` instance. (#3491)
 - Fixed issue where a pooled `NetworkObject` was not resetting the internal latest parent property when despawned. (#3491)
 - Fixed issue where the initial client synchronization pre-serialization process was not excluding spawned `NetworkObject` instances that already had pending visibility for the client being synchronized. (#3488)

com.unity.netcode.gameobjects/Runtime/NetworkVariable/Collections/NetworkList.cs

@@ -428,7 +428,7 @@ public IEnumerator<T> GetEnumerator()
         public void Add(T item)
         {
             // check write permissions
-            if (!CanClientWrite(m_NetworkManager.LocalClientId))
+            if (LocalClientCannotWrite())
             {
                 LogWritePermissionError();
                 return;
@@ -455,7 +455,7 @@ public void Add(T item)
         public void Clear()
         {
             // check write permissions
-            if (!CanClientWrite(m_NetworkManager.LocalClientId))
+            if (LocalClientCannotWrite())
             {
                 LogWritePermissionError();
                 return;
@@ -493,7 +493,7 @@ public bool Contains(T item)
         public bool Remove(T item)
         {
             // check write permissions
-            if (!CanClientWrite(m_NetworkManager.LocalClientId))
+            if (LocalClientCannotWrite())
             {
                 LogWritePermissionError();
                 return false;
@@ -542,7 +542,7 @@ public int IndexOf(T item)
         public void Insert(int index, T item)
         {
             // check write permissions
-            if (!CanClientWrite(m_NetworkManager.LocalClientId))
+            if (LocalClientCannotWrite())
             {
                 LogWritePermissionError();
                 return;
@@ -578,7 +578,7 @@ public void Insert(int index, T item)
         public void RemoveAt(int index)
         {
             // check write permissions
-            if (!CanClientWrite(m_NetworkManager.LocalClientId))
+            if (LocalClientCannotWrite())
             {
                 throw new InvalidOperationException("Client is not allowed to write to this NetworkList");
             }
@@ -610,7 +610,7 @@ public T this[int index]
             set
             {
                 // check write permissions
-                if (!CanClientWrite(m_NetworkManager.LocalClientId))
+                if (LocalClientCannotWrite())
                 {
                     LogWritePermissionError();
                     return;

com.unity.netcode.gameobjects/Runtime/NetworkVariable/NetworkVariable.cs

@@ -128,7 +128,7 @@ public virtual T Value
             get => m_InternalValue;
             set
             {
-                if (m_NetworkManager && !CanClientWrite(m_NetworkManager.LocalClientId))
+                if (LocalClientCannotWrite())
                 {
                     LogWritePermissionError();
                     return;
@@ -162,7 +162,7 @@ public bool CheckDirtyState(bool forceCheck = false)
             var isDirty = base.IsDirty();
 
             // A client without permissions invoking this method should only check to assure the current value is equal to the last known current value
-            if (m_NetworkManager && !CanClientWrite(m_NetworkManager.LocalClientId))
+            if (LocalClientCannotWrite())
             {
                 // If modifications are detected, then revert back to the last known current value
                 if (!NetworkVariableSerialization<T>.AreEqual(ref m_InternalValue, ref m_InternalOriginalValue))
@@ -245,7 +245,7 @@ public override bool IsDirty()
         {
             // If the client does not have write permissions but the internal value is determined to be locally modified and we are applying updates, then we should revert
             // to the original collection value prior to applying updates (primarily for collections).
-            if (!NetworkUpdaterCheck && m_NetworkManager && !CanClientWrite(m_NetworkManager.LocalClientId) && !NetworkVariableSerialization<T>.AreEqual(ref m_InternalValue, ref m_InternalOriginalValue))
+            if (!NetworkUpdaterCheck && LocalClientCannotWrite() && !NetworkVariableSerialization<T>.AreEqual(ref m_InternalValue, ref m_InternalOriginalValue))
             {
                 NetworkVariableSerialization<T>.Duplicate(m_InternalOriginalValue, ref m_InternalValue);
                 return true;
@@ -307,7 +307,7 @@ public override void ReadDelta(FastBufferReader reader, bool keepDirtyDelta)
         {
             // If the client does not have write permissions but the internal value is determined to be locally modified and we are applying updates, then we should revert
             // to the original collection value prior to applying updates (primarily for collections).
-            if (m_NetworkManager && !CanClientWrite(m_NetworkManager.LocalClientId) && !NetworkVariableSerialization<T>.AreEqual(ref m_InternalOriginalValue, ref m_InternalValue))
+            if (LocalClientCannotWrite() && !NetworkVariableSerialization<T>.AreEqual(ref m_InternalOriginalValue, ref m_InternalValue))
             {
                 NetworkVariableSerialization<T>.Duplicate(m_InternalOriginalValue, ref m_InternalValue);
             }
@@ -349,7 +349,7 @@ public override void ReadField(FastBufferReader reader)
         {
             // If the client does not have write permissions but the internal value is determined to be locally modified and we are applying updates, then we should revert
             // to the original collection value prior to applying updates (primarily for collections).
-            if (m_NetworkManager && !CanClientWrite(m_NetworkManager.LocalClientId) && !NetworkVariableSerialization<T>.AreEqual(ref m_InternalOriginalValue, ref m_InternalValue))
+            if (LocalClientCannotWrite() && !NetworkVariableSerialization<T>.AreEqual(ref m_InternalOriginalValue, ref m_InternalValue))
             {
                 NetworkVariableSerialization<T>.Duplicate(m_InternalOriginalValue, ref m_InternalValue);
             }

com.unity.netcode.gameobjects/Runtime/NetworkVariable/NetworkVariableBase.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Runtime.CompilerServices;
 using UnityEngine;
 
 namespace Unity.Netcode
@@ -381,6 +382,16 @@ public bool CanClientWrite(ulong clientId)
             }
         }
 
+        /// <summary>
+        /// Catches if the current <see cref="NetworkManager.LocalClientId"/> is not valid to write to this variable.
+        /// </summary>
+        /// <returns>false if the current <see cref="NetworkManager.LocalClientId"/> can write to this variable, true otherwise</returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        internal bool LocalClientCannotWrite()
+        {
+            return m_NetworkManager && !CanClientWrite(m_NetworkManager.LocalClientId);
+        }
+
         /// <summary>
         /// Returns the ClientId of the owning client
         /// </summary>