OpenGlControlBase.EnsureInitializedCore: Object reference not set to an instance of an object

[hez2010]

Describe the bug

Unhandled exception. System.NullReferenceException: Object reference not set to an instance of an object.
   at Avalonia.OpenGL.Controls.OpenGlControlBase.EnsureInitializedCore() in E:\source\repos\Avalonia\src\Avalonia.OpenGL\Controls\OpenGlControlBase.cs:line 151
   at Avalonia.OpenGL.Controls.OpenGlControlBase.EnsureInitialized() in E:\source\repos\Avalonia\src\Avalonia.OpenGL\Controls\OpenGlControlBase.cs:line 215
   at Avalonia.OpenGL.Controls.OpenGlControlBase.Render(DrawingContext ) in E:\source\repos\Avalonia\src\Avalonia.OpenGL\Controls\OpenGlControlBase.cs:line 22
   at Avalonia.Rendering.Composition.CompositingRenderer.Update() in E:\source\repos\Avalonia\src\Avalonia.Base\Rendering\Composition\CompositingRenderer.cs:line 227
   at Avalonia.Threading.JobRunner.RunJobs(Nullable`1 ) in E:\source\repos\Avalonia\src\Avalonia.Base\Threading\JobRunner.cs:line 38
   at Avalonia.Win32.Win32Platform.WndProc(IntPtr , UInt32 , IntPtr , IntPtr ) in E:\source\repos\Avalonia\src\Windows\Avalonia.Win32\Win32Platform.cs:line 296
   at Avalonia.Win32.Interop.UnmanagedMethods.DispatchMessage(MSG& )
   at Avalonia.Win32.Win32Platform.RunLoop(CancellationToken ) in E:\source\repos\Avalonia\src\Windows\Avalonia.Win32\Win32Platform.cs:line 223
   at Avalonia.Threading.Dispatcher.MainLoop(CancellationToken ) in E:\source\repos\Avalonia\src\Avalonia.Base\Threading\Dispatcher.cs:line 61
   at Avalonia.Controls.ApplicationLifetimes.ClassicDesktopStyleApplicationLifetime.Start(String[] ) in E:\source\repos\Avalonia\src\Avalonia.Controls\ApplicationLifetimes\ClassicDesktopStyleApplicationLifetime.cs:line 120
   at ControlCatalog.NetCore.Program.Main(String[] ) in E:\source\repos\Avalonia\samples\ControlCatalog.NetCore\Program.cs:line 103

To Reproduce
Steps to reproduce the behavior:

1. Enable UseWgl in CC.NetCore
2. Build and run
3. Click the first menu item "Composition"
4. Press and hold the down arrow key
5. Crash

Expected behavior
No exception should happen

Analysis
CreateSharedContext can returns null without exceptions.

Desktop (please complete the following information):

• OS: Windows 11
• Version: build from master

[hez2010]

This issue has been mitigated by #8569, now failure to create additional OpenGL context will not result in crashing, instead it yields an empty context and give up further rendering.
We still need to figure out the reason for the failure after several times of OpenGL shared context creation.