Uncaught TypeError

[Leo]

this is the class, where im using the decorator.
its part of an angular 2 app.

@Injectable()
export class PictogramCategoryResource implements ApiResource {
  endpoint: string = 'pictogram_category'
  idAttribute: string = 'id' // If not provided will use 'id'

  @CheckReturn() deserialize(data): PictogramCategory {
    return data;
  }

  serialize(data) {
    return data
  }
}

unknown typeerror in native Reflect Library

function getMetadata(metadataKey, target, targetKey) {
            if (!IsObject(target)) {
                throw new TypeError();
            }
            else if (!IsUndefined(targetKey)) {
                targetKey = ToPropertyKey(targetKey);
            }
            return OrdinaryGetMetadata(metadataKey, target, targetKey);
        }