Null Reference Exception in CartesianChart.Measure with an invisible axes.

[EricEzaM]

Describe the bug
When an axis is configured with IsVisible = false a crash occurs due to an unhandled NullReferenceException. This is common if you want to have a "End" axis hidden until a series is added which is configured to display on the right hand side axis.

To Reproduce
View Model

    public class ViewModel
    {
        public Axis[] YAxes { get; set; } = new[]
        {
            new Axis() { },
            new Axis()
            {
                IsVisible = false,
            }
        };

        public ISeries[] Series { get; set; } = new[]
        {
            new LineSeries<double>
            {
                Values = new double[] { 2, 1, 3, 5, 3, 4, 6 },
                Fill = null
            }
        };
    }

Main Window

    <Window.DataContext>
        <local:ViewModel/>
    </Window.DataContext>
    <lvc:CartesianChart
        Series="{Binding Series}"
        YAxes="{Binding YAxes}">

    </lvc:CartesianChart>

1. Launch the application
2. Resize the window so the chart redraws.
3. The application will crash.

Now, comment out IsVisible = false in the Axis constructor in the view model. The application will no longer crash.

Expected behavior
No crash

Desktop (please complete the following information):

• OS: Windows 10, .NET Framework 4.8

Additional context
The stack trace does not appear to be all that useful:

Expand to see stacktrace

System.NullReferenceException: Object reference not set to an instance of an object.
   at LiveChartsCore.CartesianChart`1.Measure()
   at LiveChartsCore.Chart`1.<UpdateThrottlerUnlocked>b__144_1()
   at System.Windows.Threading.DispatcherOperation.InvokeDelegateCore()
   at System.Windows.Threading.DispatcherOperation.InvokeImpl()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Windows.Threading.DispatcherOperation.Wait(TimeSpan timeout)
   at System.Windows.Threading.Dispatcher.InvokeImpl(DispatcherOperation operation, CancellationToken cancellationToken, TimeSpan timeout)
   at System.Windows.Threading.Dispatcher.Invoke(Action callback, DispatcherPriority priority, CancellationToken cancellationToken, TimeSpan timeout)
   at System.Windows.Threading.Dispatcher.Invoke(Action callback)
   at LiveChartsCore.SkiaSharpView.WPF.Chart.LiveChartsCore.Kernel.Sketches.IChartView.InvokeOnUIThread(Action action)
   at LiveChartsCore.Chart`1.<UpdateThrottlerUnlocked>b__144_0()
   at System.Threading.Tasks.Task.InnerInvoke()
   at System.Threading.Tasks.Task.Execute()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at LiveChartsCore.Kernel.ActionThrottler.<Call>d__8.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.AsyncMethodBuilderCore.<>c.<ThrowAsync>b__6_0(Object state)
   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.DispatcherOperation.InvokeImpl()
   at System.Windows.Threading.DispatcherOperation.InvokeInSecurityContext(Object state)
   at MS.Internal.CulturePreservingExecutionContext.CallbackWrapper(Object obj)
   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 MS.Internal.CulturePreservingExecutionContext.Run(CulturePreservingExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Windows.Threading.DispatcherOperation.Invoke()
   at System.Windows.Threading.Dispatcher.ProcessQueue()
   at System.Windows.Threading.Dispatcher.WndProcHook(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
   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 MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam)

[NPadrutt]

I have the same problem with the latest update.

[beto-rodriguez]

Fixed with the refenced commit an will be included in the next version of the library, thanks for the report.