Settings not saved on close/ Exception on Close

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What steps will reproduce the problem?

1. Close TikzEdt

What is the expected output? What do you see instead?

Settings should be saved but instead this exception is generated:

========== TIKZEDT UNCAUGHT EXCEPTION ======
7/15/2014 12:25:33 PM
Der Objektverweis wurde nicht auf eine Objektinstanz festgelegt.

Stack Trace:
   bei TikzEdt.TESettingsProvider.SetValue(SettingsPropertyValue propVal)
   bei TikzEdt.TESettingsProvider.SetPropertyValues(SettingsContext context, SettingsPropertyValueCollection propvals)
   bei System.Configuration.SettingsBase.SaveCore()
   bei System.Configuration.SettingsBase.Save()
   bei System.Configuration.ApplicationSettingsBase.Save()
   bei TikzEdt.MainWindow.Window_Closing(Object sender, CancelEventArgs e)
   bei System.Windows.Window.OnClosing(CancelEventArgs e)
   bei System.Windows.Window.WmClose()
   bei System.Windows.Window.WindowFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   bei System.Windows.Interop.HwndSource.PublicHooksFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   bei MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   bei MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
   bei System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   bei MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)
===== END: TIKZEDT UNCAUGHT EXCEPTION ======

The problem ocurs on all installations in our office.

What operating system and Latex distribution (Miktex/Texlive) are you
using?

Windows 7 64bit + MikTex 2.9

Original issue reported on code.google.com by adaa...@gmail.com on 15 Jul 2014 at 10:47