Add recreating test

Author: EmandM

com.unity.netcode.gameobjects/Tests/Runtime/NetworkBehaviourPrePostSpawnTests.cs

@@ -43,6 +43,10 @@ internal class NetworkBehaviourPreSpawn : NetworkBehaviour
 
             protected override void OnNetworkPreSpawn(ref NetworkManager networkManager)
             {
+                if (NetworkObject.NetworkManagerOwner == null)
+                {
+                    Assert.Fail("NetworkManagerOwner should be set before calling OnNetworkPreSpawn");
+                }
                 OnNetworkPreSpawnCalled = true;
                 // If we are the server, then set the randomly generated value (1-200).
                 // Otherwise, just set the value to 0.