check if addcomponent failed

Author: vkovec

Assets/FbxExporters/Editor/ConvertToModel.cs

@@ -418,7 +418,9 @@ public static void CopyComponents(GameObject from, GameObject to){
                     if (!toComponent) {
                         // It doesn't exist => create and copy.
                         toComponent = to.AddComponent(component.GetType());
-                        EditorJsonUtility.FromJsonOverwrite(json, toComponent);
+                        if (toComponent) {
+                            EditorJsonUtility.FromJsonOverwrite (json, toComponent);
+                        }
                     } else {
                         // It exists => copy.
                         // But we want to override that behaviour in a few