ystem.ArgumentNullException
  HResult=0x80004003
  Message=Value cannot be null.
  Source=mscorlib
  StackTrace:
   at System.Threading.Monitor.ReliableEnter(Object obj, Boolean& lockTaken)
   at Arction.Wpf.ChartingMVVM.LightningChart.ZPC()
   at Arction.Wpf.ChartingMVVM.LightningChart.BeginUpdate()
   at ns.Wpf.UserControls.EditableChart.<>c__DisplayClass19_0.<myChart_Loaded>b__0(ColorTheme theme) in C:\%PATH_TO_FILE%\EditableChart.xaml.cs:line 1115 # The line reported in the screenshot
   at System.Reactive.AnonymousObserver`1.OnNextCore(T value) in /_/Rx.NET/Source/src/System.Reactive/AnonymousObserver.cs:line 67
   at System.Reactive.ObserverBase`1.OnNext(T value) in /_/Rx.NET/Source/src/System.Reactive/ObserverBase.cs:line 34
   at Reactive.Bindings.ReactiveProperty`1.OnNextAndRaiseValueChanged(T& value)
   at Reactive.Bindings.ReactiveProperty`1.SetValue(T value)
   at Reactive.Bindings.ReactiveProperty`1.set_Value(T value)
   at Reactive.Bindings.ReactiveProperty`1.<.ctor>b__42_0(T x)
   at System.Reactive.AnonymousSafeObserver`1.OnNext(T value) in /_/Rx.NET/Source/src/System.Reactive/AnonymousSafeObserver.cs:line 43
   at System.Reactive.Linq.ObservableImpl.Select`2.Selector._.OnNext(TSource value) in /_/Rx.NET/Source/src/System.Reactive/Linq/Observable/Select.cs:line 47
   at Reactive.Bindings.Internals.ObserverNode`1.OnNext(T value)
   at Reactive.Bindings.ReactiveProperty`1.OnNextAndRaiseValueChanged(T& value)
   at Reactive.Bindings.ReactiveProperty`1.SetValue(T value)
   at Reactive.Bindings.ReactiveProperty`1.set_Value(T value)
   at NS.Services.SettingsService.Set(String settingName, Object value) in
C:\%PATH_TO_FILE%\SettingsService.cs:line 90
   at NS.ViewModels.AppSettingsDialogViewModel.<OnDialogOpened>b__46_2(SelectedTheme v) in C:\%PATH_TO_FILE%\AppSettingsDialogViewModel.cs:line 78
   at System.Reactive.AnonymousObserver`1.OnNextCore(T value) in /_/Rx.NET/Source/src/System.Reactive/AnonymousObserver.cs:line 67
   at System.Reactive.ObserverBase`1.OnNext(T value) in /_/Rx.NET/Source/src/System.Reactive/ObserverBase.cs:line 36
   at Reactive.Bindings.ReactivePropertySlim`1.OnNextAndRaiseValueChanged(T& value)
   at Reactive.Bindings.ReactivePropertySlim`1.set_Value(T value)