ArgumentNullException
   at System.Linq.Enumerable.Where[TSource](IEnumerable`1 source, Func`2 predicate)
   at ToastNotifications.Lifetime.TimeAndCountBasedLifetimeSupervisor.OnTimerTick()
   at System.Windows.Threading.DispatcherTimer.FireTick(Object unused)
   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)