fix: #573 (part 1) NetworkScenePostProcess handles NetworkIdentities …

…of all scenes except DontDestroyOnLoad. this way it works for additively loaded scenes too.

Assets/Mirror/Editor/NetworkScenePostProcess.cs

@@ -15,13 +15,16 @@ public class NetworkScenePostProcess : MonoBehaviour
         [PostProcessScene]
         public static void OnPostProcessScene()
         {
-            // find all NetworkIdentities in this scene
-            // => but really only from this scene. this avoids weird situations
+            // find all NetworkIdentities in all scenes
+            // => can't limit it to GetActiveScene() because that wouldn't work
+            //    for additive scene loads (the additively loaded scene is never
+            //    the active scene)
+            // => ignore DontDestroyOnLoad scene! this avoids weird situations
             //    like in NetworkZones when we destroy the local player and
             //    load another scene afterwards, yet the local player is still
             //    in the FindObjectsOfType result with scene=DontDestroyOnLoad
             //    for some reason
-            foreach (NetworkIdentity identity in FindObjectsOfType<NetworkIdentity>().Where(InActiveScene))
+            foreach (NetworkIdentity identity in FindObjectsOfType<NetworkIdentity>().Where(identity => identity.gameObject.scene.name != "DontDestroyOnLoad"))
             {
                 // if we had a [ConflictComponent] attribute that would be better than this check.
                 // also there is no context about which scene this is in.