NullReferenceException: 未将对象引用设置到对象的实例。
StackTrace:
   在 ToastNotifications.Display.NotificationsDisplaySupervisor.InternalDisplayNotification(INotification notification)
   在 System.Windows.Threading.Dispatcher.Invoke(Action callback, DispatcherPriority priority, CancellationToken cancellationToken, TimeSpan timeout)
   在 System.Windows.Threading.Dispatcher.Invoke(Action callback)
   在 ToastNotifications.Display.NotificationsDisplaySupervisor.DisplayNotification(INotification notification)
   在 ToastNotifications.Lifetime.TimeAndCountBasedLifetimeSupervisor.PushNotification(INotification notification)
   在 ToastNotifications.Lifetime.TimeAndCountBasedLifetimeSupervisor.CloseNotification(INotification notification)
   在 ToastNotifications.Lifetime.TimeAndCountBasedLifetimeSupervisor.OnTimerTick()
   在 System.Windows.Threading.DispatcherTimer.FireTick(Object unused)
   在 System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   在 System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)