z_EditorHelperHotkeys.cs

    [MenuItem(z_EditorPrefs.ContextMenuInHierarchyCommonPath + "/Fix Before export FBX", false)]
    public static void FixBeforeExportFbx()
    {
        if (!Selection.activeGameObject)
        {
            return;
        }

        foreach (var gameObject in Selection.gameObjects)
        {
            gameObject
                .GetComponentsInChildren<SkinnedMeshRenderer>()
                .ForEach(renderer =>
                {
                    if (renderer != null)
                        Object.DestroyImmediate(renderer);
                });
        }
        
        foreach (var gameObject in Selection.gameObjects)
        {
            gameObject
                .GetComponentsInChildren<LODGroup>(true)
                .ForEach(group =>
                {
                    Debug.Log($"Go to {group.gameObject.name}", group.gameObject);
                    
                    var lods = group.GetLODs().ToList();
                    var newLods = new List<LOD>(lods.Count);
                    
                    lods.ForEach(lod =>
                    {
                        var was = lod.renderers.Length;
                        lod.renderers = lod.renderers.WhereNotNull().ToArray();
                        newLods.Add(lod);
                        
                        var now = lod.renderers.Length;
                        if (was != now)
                            Debug.Log("Null lod renderer", group.gameObject);
                    });
                    
                    group.SetLODs(newLods.ToArray());
                });
        }
        
    }