Object reference not set to an instance of an object.

at YiGwsQOuBpRqjYt4DDV.oIfouuW583(Object , YiGwsQOuBpRqjYt4DDV )
at MT4APIGD.Zzh.wkTDNpsGgq(Int32 )
at BDMJZVp7b4DqQHSufPP.oIfouuW583(Object , Int32 hdtk, BDMJZVp7b4DqQHSufPP )
at MT4APIGD.Zzh.nsXDs0sX5Y(Object , RoutedPropertyChangedEventArgs`1 )
at System.Windows.RoutedPropertyChangedEventArgs`1.InvokeEventHandler(Delegate genericHandler, Object genericTarget)
at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
at System.Windows.UIElement.RaiseEvent(RoutedEventArgs e)
at System.Windows.Controls.TreeView.OnSelectedItemChanged(RoutedPropertyChangedEventArgs`1 e)
at System.Windows.Controls.TreeView.ChangeSelection(Object data, TreeViewItem container, Boolean selected)
at System.Windows.Controls.TreeViewItem.Select(Boolean selected)
at System.Windows.Controls.TreeViewItem.OnIsSelectedChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
at System.Windows.DependencyObject.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
at System.Windows.FrameworkElement.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
at System.Windows.DependencyObject.NotifyPropertyChange(DependencyPropertyChangedEventArgs args)
at System.Windows.DependencyObject.UpdateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry