NullReference in ShellPageRendererTracker.UpdateTabBarVisible()

[Marioo1357]

Description

Sometimes (like a 0.1%) the null reference occurs in ShellPageRendererTracker.UpdateTabBarVisible() on ios.
In this method there are not a null checks for 'ViewController' and 'Page'.

I'll attach pull request in comment that fix the crash.
There is a chance that it just replace the crash by not hiding ShellTabBar when code call it

It happens when user navigate from shell tab page to any basic ContentPage where tab bar should not be visible.
Exception catched on Shell.SetTabBarIsVisible(this, false); in page constructor:

 protected BasePage(PageViewModelBase vm) : base(vm)
    {
        Shell.SetTabBarIsVisible(this, false);
        InitializeComponent();
   }

Steps to Reproduce

No response

Link to public reproduction project repository

No response

Version with bug

9.0.21 SR2.1

Is this a regression from previous behavior?

Yes, this used to work in Xamarin.Forms

Last version that worked well

Unknown/Other

Affected platforms

iOS

Affected platform versions

iOS 17, 18

Did you find any workaround?

In attached pullrequest

Relevant log output

System.NullReferenceException: Arg_NullReferenceException\n   at Microsoft.Maui.Controls.Platform.Compatibility.ShellPageRendererTracker.UpdateTabBarVisible()\n   at Microsoft.Maui.Controls.Platform.Compatibility.ShellPageRendererTracker.UpdateShellToMyPage()\n   at Microsoft.Maui.Controls.Platform.Compatibility.ShellPageRendererTracker.SetAppeared()\n   at Microsoft.Maui.Controls.Platform.Compatibility.ShellPageRendererTracker.PageAppearing(Object sender, EventArgs e)\n   at Microsoft.Maui.Controls.Page.SendAppearing()\n   at Microsoft.Maui.Controls.Shell.SendPageAppearing(Page page)\n   at Microsoft.Maui.Controls.ShellSection.PresentedPageAppearing()\n   at Microsoft.Maui.Controls.ShellSection.\u003CPresentedPageAppearing\u003Eg_OnPresentedPageParentSet|89_0(Object sender, EventArgs e)\n   at Microsoft.Maui.Controls.Element.OnParentSet()\n   at Microsoft.Maui.Controls.NavigableElement.OnParentSet()\n   at Microsoft.Maui.Controls.Page.OnParentSet()\n   at Microsoft.Maui.Controls.Element.SetParent(Element value)\n   at Microsoft.Maui.Controls.Element.OnChildAdded(Element child)\n   at Microsoft.Maui.Controls.ShellSection.OnChildAdded(Element child)\n   at Microsoft.Maui.Controls.Element.AddLogicalChild(Element element)\n   at Microsoft.Maui.Controls.ShellSection.OnPushAsync(Page page, Boolean animated)\n   at Microsoft.Maui.Controls.ShellSection.PushStackOfPages(List\u00601 pages, Nullable\u00601 animate)\n   at Microsoft.Maui.Controls.ShellSection.GoToAsync(ShellNavigationRequest request, ShellRouteParameters queryData, IServiceProvider services, Nullable\u00601 animate, Boolean isRelativePopping)\n   at Microsoft.Maui.Controls.ShellNavigationManager.GoToAsync(ShellNavigationParameters shellNavigationParameters, ShellNavigationRequest navigationRequest)\n   at Pomelo.App.Core.Helpers.MainThreadHelper.InvokeOnMainThreadAsync(Func\u00601 action)\n   at Pomelo.App.Core.Services.Core.NavigationService.GoToAsync(String path, IDictionary\u00602 parameters, Boolean withAnimation)\n   at Pomelo.App.Core.ViewModels.Base.ViewModelBase.DoActionAsync(Task action)\n   at CommunityToolkit.Mvvm.Input.AsyncRelayCommand.AwaitAndThrowIfFailed(Task )\n   at System.Threading.Tasks.Task.\u003C\u003Ec.\u003CThrowAsync\u003Eb128_0(Object state)\n   at Foundation.NSAsyncSynchronizationContextDispatcher.Apply()","ModelException":{"Type":"System.NullReferenceException","Message":"Arg_NullReferenceException","StackTrace":"   at Microsoft.Maui.Controls.Platform.Compatibility.ShellPageRendererTracker.UpdateTabBarVisible()\n   at Microsoft.Maui.Controls.Platform.Compatibility.ShellPageRendererTracker.UpdateShellToMyPage()\n   at Microsoft.Maui.Controls.Platform.Compatibility.ShellPageRendererTracker.SetAppeared()\n   at Microsoft.Maui.Controls.Platform.Compatibility.ShellPageRendererTracker.PageAppearing(Object sender, EventArgs e)\n   at Microsoft.Maui.Controls.Page.SendAppearing()\n   at Microsoft.Maui.Controls.Shell.SendPageAppearing(Page page)\n   at Microsoft.Maui.Controls.ShellSection.PresentedPageAppearing()\n   at Microsoft.Maui.Controls.ShellSection.\u003CPresentedPageAppearing\u003EgOnPresentedPageParentSet|89_0(Object sender, EventArgs e)\n   at Microsoft.Maui.Controls.Element.OnParentSet()\n   at Microsoft.Maui.Controls.NavigableElement.OnParentSet()\n   at Microsoft.Maui.Controls.Page.OnParentSet()\n   at Microsoft.Maui.Controls.Element.SetParent(Element value)\n   at Microsoft.Maui.Controls.Element.OnChildAdded(Element child)\n   at Microsoft.Maui.Controls.ShellSection.OnChildAdded(Element child)\n   at Microsoft.Maui.Controls.Element.AddLogicalChild(Element element)\n   at Microsoft.Maui.Controls.ShellSection.OnPushAsync(Page page, Boolean animated)\n   at Microsoft.Maui.Controls.ShellSection.PushStackOfPages(List\u00601 pages, Nullable\u00601 animate)\n   at Microsoft.Maui.Controls.ShellSection.GoToAsync(ShellNavigationRequest request, ShellRouteParameters queryData, IServiceProvider services, Nullable\u00601 animate, Boolean isRelativePopping)\n   at Microsoft.Maui.Controls.ShellNavigationManager.GoToAsync(ShellNavigationParameters shellNavigationParameters, ShellNavigationRequest navigationRequest)\n   at Pomelo.App.Core.Helpers.MainThreadHelper.InvokeOnMainThreadAsync(Func\u00601 action)\n   at Pomelo.App.Core.Services.Core.NavigationService.GoToAsync(String path, IDictionary\u00602 parameters, Boolean withAnimation)\n   at Pomelo.App.Core.ViewModels.Base.ViewModelBase.DoActionAsync(Task action)\n   at CommunityToolkit.Mvvm.Input.AsyncRelayCommand.AwaitAndThrowIfFailed(Task )\n   at System.Threading.Tasks.Task.\u003C\u003Ec.\u003CThrowAsync\u003Eb_128_0(Object state)\n   at Foundation.NSAsyncSynchronizationContextDispatcher.Apply()","Frames":[

{"ClassName":"Microsoft.Maui.Controls.Platform.Compatibility.ShellPageRendererTracker","MethodName":"UpdateTabBarVisible","FileName":null,"LineNumber":null}
,{"ClassName":"Microsoft.Maui.Controls.Platform.Compatibility.ShellPageRendererTracker","MethodName":"UpdateShellToMyPage","FileName":null,"LineNumber":null},{"ClassName":"Microsoft.Maui.Controls.Platform.Compatibility.ShellPageRendererTracker","MethodName":"SetAppeared","FileName":null,"LineNumber":null},{"ClassName":"Microsoft.Maui.Controls.Platform.Compatibility.ShellPageRendererTracker","MethodName":"PageAppearing","FileName":null,"LineNumber":null},{"ClassName":null,"MethodName":null,"FileName":null,"LineNumber":null},{"ClassName":"Microsoft.Maui.Controls.Page","MethodName":"SendAppearing","FileName":null,"LineNumber":null},{"ClassName":"Microsoft.Maui.Controls.Shell","MethodName":"SendPageAppearing","FileName":null,"LineNumber":null},{"ClassName":"Microsoft.Maui.Controls.ShellSection","MethodName":"PresentedPageAppearing","FileName":null,"LineNumber":null},{"ClassName":"Microsoft.Maui.Controls.ShellSection","MethodName":"\u003CPresentedPageAppearing\u003Eg_OnPresentedPageParentSet|89_0","FileName":null,"LineNumber":null},{"ClassName":"Microsoft.Maui.Controls.Element","MethodName":"OnParentSet","FileName":null,"LineNumber":null},{"ClassName":"Microsoft.Maui.Controls.NavigableElement","MethodName":"OnParentSet","FileName":null,"LineNumber":null},{"ClassName":"Microsoft.Maui.Controls.Page","MethodName":"OnParentSet","FileName":null,"LineNumber":null},{"ClassName":"Microsoft.Maui.Controls.Element","MethodName":"SetParent","FileName":null,"LineNumber":null},{"ClassName":"Microsoft.Maui.Controls.Element","MethodName":"OnChildAdded","FileName":null,"LineNumber":null},{"ClassName":"Microsoft.Maui.Controls.ShellSection","MethodName":"OnChildAdded","FileName":null,"LineNumber":null},{"ClassName":"Microsoft.Maui.Controls.Element","MethodName":"AddLogicalChild","FileName":null,"LineNumber":null},{"ClassName":"Microsoft.Maui.Controls.ShellSection","MethodName":"OnPushAsync","FileName":null,"LineNumber":null},{"ClassName":"Microsoft.Maui.Controls.ShellSection\u002B\u003CPushStackOfPages\u003Ed68","MethodName":"MoveNext","FileName":null,"LineNumber":null},{"ClassName":"System.Runtime.ExceptionServices.ExceptionDispatchInfo","MethodName":"Throw","FileName":null,"LineNumber":null},{"ClassName":"System.Runtime.CompilerServices.TaskAwaiter","MethodName":"ThrowForNonSuccess","FileName":null,"LineNumber":null},{"ClassName":"System.Runtime.CompilerServices.TaskAwaiter","MethodName":"HandleNonSuccessAndDebuggerNotification","FileName":null,"LineNumber":null},{"ClassName":"Microsoft.Maui.Controls.ShellSection\u002B\u003CGoToAsync\u003Ed65","MethodName":"MoveNext","FileName":null,"LineNumber":null},{"ClassName":"System.Runtime.ExceptionServices.ExceptionDispatchInfo","MethodName":"Throw","FileName":null,"LineNumber":null},{"ClassName":"System.Runtime.CompilerServices.TaskAwaiter","MethodName":"ThrowForNonSuccess","FileName":null,"LineNumber":null},{"ClassName":"System.Runtime.CompilerServices.TaskAwaiter","MethodName":"HandleNonSuccessAndDebuggerNotification","FileName":null,"LineNumber":null},{"ClassName":"Microsoft.Maui.Controls.ShellNavigationManager\u002B\u003CGoToAsync\u003Ed14","MethodName":"MoveNext","FileName":null,"LineNumber":null},{"ClassName":"System.Runtime.ExceptionServices.ExceptionDispatchInfo","MethodName":"Throw","FileName":null,"LineNumber":null},{"ClassName":"System.Runtime.CompilerServices.TaskAwaiter","MethodName":"ThrowForNonSuccess","FileName":null,"LineNumber":null},{"ClassName":"System.Runtime.CompilerServices.TaskAwaiter","MethodName":"HandleNonSuccessAndDebuggerNotification","FileName":null,"LineNumber":null}