Need to reset SortComparer...setting null causes crash

[Ken]

I just want to make sure I'm doing this correctly.  In my constructor I have this:
            HamsGrid.MasterTemplate.SortComparer = new HamsCustomComparer();

That works as expected.  Now I also want the user to be able to sort individual columns if they so choose, so I added two radio buttons to the screen, one called Default the other User.  When User is clicked I want to clear the custom comparer, so I do this:

            HamsGrid.MasterTemplate.SortComparer = null; //line 1807 in code

Then, of course in the Default handler I have:
            HamsGrid.MasterTemplate.SortComparer = new HamsCustomComparer();

Setting it to null is causing an exception (I only have from my call at line 1807 on up):
System.NullReferenceException: Object reference not set to an instance of an object.
   at Telerik.Collections.Generic.AvlTree`1.LastIndex(ValueT value)
   at Telerik.Collections.Generic.AvlTree`1.InsertWithDuplicates(ValueT value)
   at Telerik.Collections.Generic.AvlTree`1.Add(ValueT item)
   at Telerik.WinControls.Data.AvlIndex`1.Perform()
   at Telerik.WinControls.Data.AvlIndex`1.get_Items()
   at Telerik.WinControls.Data.RadDataView`1.get_Items()
   at Telerik.WinControls.Data.RadCollectionView`1.GetEnumerator()
   at Telerik.WinControls.UI.GridViewInfo.Refresh()
   at Telerik.WinControls.UI.GridViewInfo.get_ChildRows()
   at Telerik.WinControls.UI.GridViewTemplate.get_ChildRows()
   at Telerik.WinControls.UI.ViewInfoTraverser.SetCollectionForStage(Boolean initializeCollection)
   at Telerik.WinControls.UI.ViewInfoTraverser.SetCollectionForStage()
   at Telerik.WinControls.UI.ViewInfoTraverser.ChangeCollectionForward()
   at Telerik.WinControls.UI.ViewInfoTraverser.MoveNextCore()
   at Telerik.WinControls.UI.ViewInfoTraverser.MoveNext()
   at Telerik.WinControls.UI.GridTraverser.MoveNextCore()
   at Telerik.WinControls.UI.GridTraverser.MoveNext()
   at Telerik.WinControls.UI.ItemScroller`1.UpdateScrollRange()
   at Telerik.WinControls.UI.RowScroller.UpdateScrollRange()
   at Telerik.WinControls.UI.GridTableElement.UpdateNoDataText()
   at Telerik.WinControls.UI.GridTableElement.UpdateAll()
   at Telerik.WinControls.UI.GridTableElement.UpdateViewCore(Object sender, DataViewChangedEventArgs args)
   at Telerik.WinControls.UI.GridTableElement.UpdateView(Object sender, DataViewChangedEventArgs args)
   at Telerik.WinControls.UI.GridTableElement.ProcessTemplateEvent(GridViewEvent eventData)
   at Telerik.WinControls.UI.GridTableElement.Telerik.WinControls.UI.IGridViewEventListener.ProcessEvent(GridViewEvent eventData)
   at Telerik.WinControls.UI.GridViewEventProcessEntity.ProcessCollection(GridViewEvent gridEvent, PriorityWeakReferenceList list, GridEventProcessMode processMode)
   at Telerik.WinControls.UI.GridViewEventProcessEntity.Process(GridViewEvent gridEvent)
   at Telerik.WinControls.UI.GridViewEventProcessEntity.ProcessEvent(GridViewEvent gridEvent)
   at Telerik.WinControls.UI.GridViewSynchronizationService.NotifyListeners(GridViewEvent gridEvent)
   at Telerik.WinControls.UI.GridViewSynchronizationService.FlushEvents()
   at Telerik.WinControls.UI.GridViewSynchronizationService.DispatchEvent(GridViewEvent gridEvent)
   at Telerik.WinControls.UI.GridViewSynchronizationService.DispatchEvent(GridViewTemplate template, GridViewEvent eventData, Boolean postUI)
   at Telerik.WinControls.UI.GridViewTemplate.DispatchEvent(GridViewEvent gridEvent, Boolean postUI)
   at Telerik.WinControls.UI.GridViewTemplate.DispatchDataViewChangedEvent(Object sender, DataViewChangedEventArgs args)
   at Telerik.WinControls.UI.GridViewTemplate.OnViewChanged(Object sender, DataViewChangedEventArgs e)
   at Telerik.WinControls.UI.GridViewTemplate.OnViewChanged(DataViewChangedEventArgs e)
   at Telerik.WinControls.UI.GridViewTemplate.CollectionView_CollectionChanged(Object sender, NotifyCollectionChangedEventArgs e)
   at Telerik.WinControls.Data.RadCollectionView`1.OnCollectionChanged(NotifyCollectionChangedEventArgs args)
   at Telerik.WinControls.Data.RadDataView`1.RebuildData(Boolean notify)
   at Telerik.WinControls.Data.RadDataView`1.RefreshOverride()
   at Telerik.WinControls.Data.RadDataView`1.OnNotifyPropertyChanged(PropertyChangedEventArgs e)
   at Telerik.WinControls.Data.RadDataView`1.set_Comparer(IComparer`1 value)
   at Telerik.WinControls.UI.GridViewTemplate.set_SortComparer(IComparer`1 value)
   at TCS.TDOC.DispatchScreen.SortCustomRadio_ToggleStateChanged(Object sender, StateChangedEventArgs args) in C:\Work\TCS\Source\TCS\TCS\ContentScreens\DispatchScreen.cs:line 1807

[Svett]

Hello Ken,

You should not set the Comparer property to Null. Instead, you should set it to the default one in the following way:

this.radGridView1.MasterTemplate.SortComparer = new
            GridViewRowInfoComparer(this.radGridView1.MasterTemplate.SortDescriptors);

Kind regards,
Svett
the Telerik team