NumericUpDown Exception raised when trying to enter a number in scientific notation

[Gimly]

A NullReferenceException is raised in the NumericUpDown when trying to enter a number with the scientific notation and the StringFormat is not set correctly.

It's the StringFormat property that is null and raises the exception.
Exception details:

System.NullReferenceException was unhandled
  HResult=-2147467261
  Message=Object reference not set to an instance of an object.
  Source=MahApps.Metro
  StackTrace:
       at MahApps.Metro.Controls.NumericUpDown.OnPreviewTextInput(Object sender, TextCompositionEventArgs e) in c:\Projects\Git\MahApps.Metro\MahApps.Metro\Controls\NumericUpDown.cs:line 369
       at System.Windows.Input.TextCompositionEventArgs.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.RaiseTrustedEvent(RoutedEventArgs args)
       at System.Windows.UIElement.RaiseEvent(RoutedEventArgs args, Boolean trusted)
       at System.Windows.Input.InputManager.ProcessStagingArea()
       at System.Windows.Input.InputManager.ProcessInput(InputEventArgs input)
       at System.Windows.Input.TextCompositionManager.UnsafeCompleteComposition(TextComposition composition)
       at System.Windows.Input.TextCompositionManager.PostProcessInput(Object sender, ProcessInputEventArgs e)
       at System.Windows.Input.InputManager.RaiseProcessInputEventHandlers(ProcessInputEventHandler postProcessInput, ProcessInputEventArgs processInputEventArgs)
       at System.Windows.Input.InputManager.ProcessStagingArea()
       at System.Windows.Input.InputManager.ProcessInput(InputEventArgs input)
       at System.Windows.Input.TextCompositionManager.UnsafeStartComposition(TextComposition composition)
       at System.Windows.Input.TextCompositionManager.PostProcessInput(Object sender, ProcessInputEventArgs e)
       at System.Windows.Input.InputManager.RaiseProcessInputEventHandlers(ProcessInputEventHandler postProcessInput, ProcessInputEventArgs processInputEventArgs)
       at System.Windows.Input.InputManager.ProcessStagingArea()
       at System.Windows.Input.InputManager.ProcessInput(InputEventArgs input)
       at System.Windows.Input.InputProviderSite.ReportInput(InputReport inputReport)
       at System.Windows.Interop.HwndKeyboardInputProvider.ProcessTextInputAction(IntPtr hwnd, WindowMessage msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
       at System.Windows.Interop.HwndSource.OnPreprocessMessage(Object param)
       at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
       at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, 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.HwndSource.WeakEventPreprocessMessage.OnPreprocessMessage(MSG& msg, Boolean& handled)
       at System.Windows.Interop.ThreadMessageEventHandler.Invoke(MSG& msg, Boolean& handled)
       at System.Windows.Interop.ComponentDispatcherThread.RaiseThreadMessage(MSG& msg)
       at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame)
       at System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame)
       at System.Windows.Threading.Dispatcher.Run()
       at System.Windows.Application.RunDispatcher(Object ignore)
       at System.Windows.Application.RunInternal(Window window)
       at System.Windows.Application.Run(Window window)
       at System.Windows.Application.Run()
       at MetroDemo.App.Main() in c:\Projects\Git\MahApps.Metro\samples\MetroDemo\obj\NET45\Debug\App.g.cs:line 0
       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()
  InnerException: 

This can be tested with the demo app if you try adding 1E to the second NumericUpDown in the Text tab.

The scientific notation should be a valid entry even if the StringFormat is not of a scientific notation type I think.