   @available(iOS 10.0, *)
   lazy public var persistentContainer: NSPersistentContainer = {
     let container = NSPersistentContainer(name: persistentContainerName)
-    container.persistentStoreDescriptions = persistentStoreDescriptions
+    if let descriptions = persistentStoreDescriptions {
+      container.persistentStoreDescriptions = descriptions
+    }
     return container
   }()
   

  
  init() {
    persistentContainerName = kDefatultContainerName
    let description = NSPersistentStoreDescription()
    description.type = NSSQLiteStoreType
    persistentStoreDescriptions = [description]
  }
  
  // MARK: - PersistentStore
  
  public var persistentContainerName: String!
  public var persistentStoreDescriptions: Array<NSPersistentStoreDescription>!
  
  public var savingContext: NSManagedObjectContext {
    get {

    persistentContainer.loadPersistentStores(completionHandler: block)
  }
}
