TextPointer is not in the TextTree associated with this object

[wyl2008056]

System.ArgumentException: TextPointer is not in the TextTree associated with this object。
at System.Windows.Documents.ValidationHelper.VerifyPosition(ITextContainer container, ITextPointer position, String paramName)
at System.Windows.Documents.TextPointer.CompareTo(TextPointer position)
at Simple.Wpf.Terminal.Terminal.HandleBackspaceKey()
at Simple.Wpf.Terminal.Terminal.OnPreviewKeyDown(KeyEventArgs args)
at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
at System.Windows.UIElement.RaiseTrustedEvent(RoutedEventArgs args)
at System.Windows.Input.InputManager.ProcessStagingArea()
at System.Windows.Input.InputProviderSite.ReportInput(InputReport inputReport)
at System.Windows.Interop.HwndKeyboardInputProvider.ProcessKeyAction(MSG& msg, Boolean& handled)
at System.Windows.Interop.HwndSource.CriticalTranslateAccelerator(MSG& msg, ModifierKeys modifiers)
at System.Windows.Interop.HwndSource.OnPreprocessMessage(Object param)
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)
at System.Windows.Threading.Dispatcher.LegacyInvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Int32 numArgs)
at System.Windows.Threading.Dispatcher.Invoke(DispatcherPriority priority, Delegate method, Object arg)
at System.Windows.Interop.HwndSource.OnPreprocessMessageThunk(MSG& msg, Boolean& handled)
at System.Windows.Interop.ComponentDispatcherThread.RaiseThreadMessage(MSG& msg)
at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame)
at System.Windows.Application.RunDispatcher(Object ignore)
at System.Windows.Application.RunInternal(Window window)
at GaugeTool.App.Main()

Version 2.3.75
This proble is always present, in follow step:
1、Change the input method to Chinese.
2、Input anything in terminal control