fix

Fixing exception that could be thrown in NetworkLog if there is no NetworkManager instance.
Adding additional check in NetworkObject.OnNetworkBehaviourDestroyed to assure nothing is ever logged about destroying a NetworkBehaviour when shutting down and the NetworkObject is still considered spawned.

Author: NoelStephensUnity

com.unity.netcode.gameobjects/Runtime/Core/NetworkObject.cs

@@ -3647,7 +3647,8 @@ internal void OnNetworkBehaviourDestroyed(NetworkBehaviour networkBehaviour)
         {
             if (networkBehaviour.IsSpawned && IsSpawned)
             {
-                if (NetworkManagerOwner.LogLevel <= LogLevel.Developer)
+                // Only log this warning if we are not shutting down.
+                if (!NetworkManagerOwner.ShutdownInProgress && NetworkManagerOwner.LogLevel <= LogLevel.Developer)
                 {
                     NetworkLog.LogWarning($"{nameof(NetworkBehaviour)}-{networkBehaviour.name} is being destroyed while {nameof(NetworkObject)}-{name} is still spawned! (could break state synchronization)");
                 }

com.unity.netcode.gameobjects/Runtime/Logging/NetworkLog.cs

@@ -113,14 +113,21 @@ private static void LogServer(string message, LogType logType)
             }
         }
 
+        private const string k_HeaderStart = "Netcode";
         private static string Header()
         {
             var networkManager = NetworkManagerOverride ??= NetworkManager.Singleton;
-            if (networkManager.DistributedAuthorityMode)
+            if (networkManager != null)
             {
-                return "Session-Owner";
+                if (networkManager.DistributedAuthorityMode)
+                {
+                    return $"{k_HeaderStart}-Session-Owner";
+                }
+                return $"{k_HeaderStart}-Server";
             }
-            return "Netcode-Server";
+
+            // If NetworkManager no longer exists, then return the generic header
+            return k_HeaderStart;
         }
 
         internal static void LogInfoServerLocal(string message, ulong sender) => Debug.Log($"[{Header()} Sender={sender}] {message}");