// Manager integrity and reset
        private void checkValidity()
        {
            SketchfabPlugin.checkValidity();
            if (_api == null)
            {
                _api = SketchfabPlugin.getAPI();
            }

            if (_sketchfabModels == null)
            {
                _sketchfabModels = new OrderedDictionary();
            }

            if (_categories == null)
            {
                fetchCategories();
            }

            if (_importer == null)
            {
                _importer = new SketchfabImporter(ImportProgress, ImportFinish);
            }
        }