Exception Message:
Object reference not set to an instance of an object

Exception Stack:
   at Telerik.Maui.Data.ParallelDataEngine.Telerik.Maui.Data.IDataEngine.RebuildAggregatesForItem(Object item, String propertyName)
   at Telerik.Maui.Data.LocalDataSourceProvider.ProcessPropertyChangedOverride(Object sender, PropertyChangedEventArgs args)
   at Telerik.Maui.Data.LocalDataSourceProvider.DataView_ItemPropertyChanged(Object sender, PropertyChangedEventArgs e)
   at Telerik.Maui.Data.EnumerableDataSourceView.Telerik.Maui.IWeakEventListener.ReceiveEvent(Object sender, Object args)
   at Fmr.Sirius.ComponentModel.ObservableObject.FirePropertyChanged(IEnumerable`1 propertyChanges)
   at System.Reactive.AnonymousSafeObserver`1.OnNext(T value)
   at System.Reactive.Concurrency.AsyncLock.Wait(Object state, Delegate delegate, Action`2 action)
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location ---
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.TimerQueueTimer.System.Threading.IThreadPoolWorkItem.Execute()
   at System.Threading.ThreadPoolWorkQueue.Dispatch()
   at System.Threading.PortableThreadPool.WorkerThread.WorkerThreadStart()
   at System.Threading.Thread.StartCallback()

Exception.Stack 2:

   at Telerik.Maui.Data.ParallelDataEngine.Telerik.Maui.Data.IDataEngine.RebuildAggregatesForItem(Object item, String propertyName)
   at Telerik.Maui.Data.LocalDataSourceProvider.ProcessPropertyChangedOverride(Object sender, PropertyChangedEventArgs args)
   at Telerik.Maui.Data.LocalDataSourceProvider.DataView_ItemPropertyChanged(Object sender, PropertyChangedEventArgs e)
   at Telerik.Maui.Data.EnumerableDataSourceView.Telerik.Maui.IWeakEventListener.ReceiveEvent(Object sender, Object args)
   at Fmr.Sirius.ComponentModel.ObservableObject.FirePropertyChanged(IEnumerable`1 propertyChanges)
   at System.Reactive.AnonymousSafeObserver`1.OnNext(T value)
   at System.Reactive.Linq.ObservableImpl.Sample`1._.Tick()
   at System.Reactive.Concurrency.DefaultScheduler.PeriodicallyScheduledWorkItem`1.<>c.<Tick>b__5_0(PeriodicallyScheduledWorkItem`1 closureWorkItem)
   at System.Reactive.Concurrency.AsyncLock.Wait(Object state, Delegate delegate, Action`2 action)
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location ---
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.TimerQueueTimer.System.Threading.IThreadPoolWorkItem.Execute()
   at System.Threading.ThreadPoolWorkQueue.Dispatch()
   at System.Threading.PortableThreadPool.WorkerThread.WorkerThreadStart()
   at System.Threading.Thread.StartCallback()