From e321c30c1d06204e0a631168d35c8803b696c71e Mon Sep 17 00:00:00 2001
From: Wojtek Figat <wojtek@figat.pl>
Date: Fri, 3 Sep 2021 14:31:31 +0200
Subject: [PATCH] Fix crash on NestedSceneAnimationTrack load without timeline

---
 .../Tracks/NestedSceneAnimationTrack.cs       | 21 +++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/Source/Editor/GUI/Timeline/Tracks/NestedSceneAnimationTrack.cs b/Source/Editor/GUI/Timeline/Tracks/NestedSceneAnimationTrack.cs
index d42b06d9b..df24b0d5c 100644
--- a/Source/Editor/GUI/Timeline/Tracks/NestedSceneAnimationTrack.cs
+++ b/Source/Editor/GUI/Timeline/Tracks/NestedSceneAnimationTrack.cs
@@ -128,18 +128,31 @@ namespace FlaxEditor.GUI.Timeline.Tracks
         /// <inheritdoc />
         protected override void OnAssetChanged()
         {
-            if (Asset)
+            base.OnAssetChanged();
+
+            CheckCyclicReferences();
+        }
+
+        /// <inheritdoc />
+        public override void OnTimelineChanged(Timeline timeline)
+        {
+            base.OnTimelineChanged(timeline);
+
+            CheckCyclicReferences();
+        }
+
+        private void CheckCyclicReferences()
+        {
+            if (Asset && Timeline is SceneAnimationTimeline timeline)
             {
                 var refs = Asset.GetReferences();
-                var id = ((SceneAnimationTimeline)Timeline)._id;
+                var id = timeline._id;
                 if (Asset.ID == id || refs.Contains(id))
                 {
                     Asset = null;
                     throw new Exception("Cannot use nested scene animation (recursion).");
                 }
             }
-
-            base.OnAssetChanged();
         }
     }
 }