Make null ( not deserializable ) objects part of undo state (#86)

Author: iTris666

com.unity.visualeffectgraph/Editor/Models/VFXGraph.cs

@@ -294,11 +294,7 @@ public object Backup()
             dependencies.Add(this);
             CollectDependencies(dependencies);
 
-            // This is a guard where dependencies that couldnt be deserialized (because script is missing for instance) are removed from the list
-            // because else StoreObjectsToByteArray is crashing
-            // TODO Fix that
-            var safeDependencies = dependencies.Where(o => o != null);
-            var result = VFXMemorySerializer.StoreObjectsToByteArray(safeDependencies.ToArray(), CompressionLevel.Fastest);
+            var result = VFXMemorySerializer.StoreObjectsToByteArray(dependencies.ToArray(), CompressionLevel.Fastest);
 
             Profiler.EndSample();