Game crashed

[AirBerliner]

Code:

Version: Version 2.14 Patch B (Alpha)
05.08.2019: 18:42 System.NullReferenceException: Der Objektverweis wurde nicht auf eine Objektinstanz festgelegt.
  bei TheAirlineProjectV2.Infrastructure.Model.LoadSaveModel.Converters.AirlinerClassesConverter.<>c.<ConvertTo>b__6_0(FacilityOptionType o) in D:\OneDrive\bureaublad\TAP\TAP Code\TheAirlineProjectV2.Infrastructure\Model\LoadSaveModel\Converters\AirlinerClassesConverter.cs:Zeile 148.
  bei System.Linq.Enumerable.WhereSelectListIterator`2.MoveNext()
  bei System.String.Join(String separator, IEnumerable`1 values)
  bei TheAirlineProjectV2.Infrastructure.Model.LoadSaveModel.Converters.AirlinerClassesConverter.ConvertTo(ITypeDescriptorContext context, CultureInfo culture, Object value, Type destinationType) in D:\OneDrive\bureaublad\TAP\TAP Code\TheAirlineProjectV2.Infrastructure\Model\LoadSaveModel\Converters\AirlinerClassesConverter.cs:Zeile 148.
  bei System.ComponentModel.TypeConverter.ConvertTo(Object value, Type destinationType)
  bei SQLiter.SQLiter.getPropertyValue(Object type, PropertyInfo property) in C:\Users\Christian\Documents\Visual Studio 2017\Projects\SQLiter\SQLiter\SQLiter.cs:Zeile 450.
  bei SQLiter.SQLiter.SaveAll[T](IEnumerable`1 data) in C:\Users\Christian\Documents\Visual Studio 2017\Projects\SQLiter\SQLiter\SQLiter.cs:Zeile 175.
  bei TheAirlineProjectV2.Infrastructure.Model.LoadSaveModel.LoadSaveHelpers.SaveGame(SaveFile save) in D:\OneDrive\bureaublad\TAP\TAP Code\TheAirlineProjectV2.Infrastructure\Model\LoadSaveModel\LoadSaveHelpers.cs:Zeile 376.
  bei TheAirlineProjectV2.Infrastructure.Model.LoadSaveModel.LoadSaveObject.saveGame(SaveFile savefile) in D:\OneDrive\bureaublad\TAP\TAP Code\TheAirlineProjectV2.Infrastructure\Model\LoadSaveModel\LoadSaveObject.cs:Zeile 244.
  bei TheAirlineProjectV2.Modules.GameSideMenu.ViewModels.GameSideMenuViewModel.MenuItemClicked(Object o) in D:\OneDrive\bureaublad\TAP\TAP Code\TheAirlineProjectV2.Modules.GameSideMenu\ViewModels\GameSideMenuViewModel.cs:Zeile 224.
  bei Prism.Commands.DelegateCommand`1.Execute(T parameter)
  bei Prism.Commands.DelegateCommand`1.Execute(Object parameter)
  bei Prism.Commands.DelegateCommandBase.System.Windows.Input.ICommand.Execute(Object parameter)
  bei MS.Internal.Commands.CommandHelpers.CriticalExecuteCommandSource(ICommandSource commandSource, Boolean userInitiated)
  bei System.Windows.Documents.Hyperlink.OnClick()
  bei System.Windows.Documents.Hyperlink.DispatchNavigation(Object sender)
  bei System.Windows.Documents.Hyperlink.DoUserInitiatedNavigation(Object sender)
  bei System.Windows.Documents.Hyperlink.OnMouseLeftButtonUp(Object sender, MouseButtonEventArgs e)
  bei System.Windows.Documents.Hyperlink.OnMouseLeftButtonUp(MouseButtonEventArgs e)
  bei System.Windows.UIElement.OnMouseLeftButtonUpThunk(Object sender, MouseButtonEventArgs e)
  bei System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget)
  bei System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
  bei System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
  bei System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
  bei System.Windows.UIElement.ReRaiseEventAs(DependencyObject sender, RoutedEventArgs args, RoutedEvent newEvent)
  bei System.Windows.UIElement.OnMouseUpThunk(Object sender, MouseButtonEventArgs e)
  bei System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget)
  bei System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
  bei System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
  bei System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
  bei System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
  bei System.Windows.ContentElement.RaiseTrustedEvent(RoutedEventArgs args)
  bei System.Windows.Input.InputManager.ProcessStagingArea()
  bei System.Windows.Input.InputManager.ProcessInput(InputEventArgs input)
  bei System.Windows.Input.InputProviderSite.ReportInput(InputReport inputReport)
  bei System.Windows.Interop.HwndMouseInputProvider.ReportInput(IntPtr hwnd, InputMode mode, Int32 timestamp, RawMouseActions actions, Int32 x, Int32 y, Int32 wheel)
  bei System.Windows.Interop.HwndMouseInputProvider.FilterMessage(IntPtr hwnd, WindowMessage msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
  bei System.Windows.Interop.HwndSource.InputFilterMessage(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 System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)
  bei System.Windows.Threading.Dispatcher.LegacyInvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Int32 numArgs)
  bei MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam)
  bei MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg)
  bei System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame)
  bei System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame)
  bei System.Windows.Application.RunDispatcher(Object ignore)
  bei System.Windows.Application.RunInternal(Window window)
  bei System.Windows.Application.Run(Window window)
  bei System.Windows.Application.Run()
  bei TheAirlineProjectV2.App.Main()

I hope the bug is new.

The game crashe with saving. The save data can I see in the load menu, but it doesn't load. When loading the game crashed.