Problem with app.razor, why can't I add the @code section?

razor

@inject IVisibilityService VisibilityService<CascadingAuthenticationState><Router AppAssembly="@typeof(Program).Assembly"><Found Context="routeData"><AuthorizeRouteView RouteData="@routeData" DefaultLayout="@typeof(MainLayout)"><NotAuthorized><h1>Access Denied</h1><p>You are not authorized to access this resource.</p></NotAuthorized></AuthorizeRouteView></Found><NotFound><LayoutView Layout="@typeof(MainLayout)"><p role="alert">Sorry, there's nothing at this address.</p></LayoutView></NotFound></Router></CascadingAuthenticationState>@code {    private bool isActiveTab = true;    protected override async Task OnInitializedAsync()    {        VisibilityService.OnVisible += OnTabVisible;        VisibilityService.OnHidden += OnTabHidden;        await VisibilityService.Initialize();    }    private async void OnTabVisible()    {        // Example logic when tab becomes visible        Console.WriteLine("Tab is visible");    }    private async void OnTabHidden()    {        // Example logic when tab becomes hidden        Console.WriteLine("Tab is hidden");    }}

it keeps giving me an error:"RZ1006 The code block is missing a closing "}" character. Make sure you have a matching "}" character for all the "{" characters within this block, and that none of the "}" characters are being interpreted as markup. "as if he didn't like the mountain of code itself

I want to add logic that if the tab is not active, it should close the thread so as not to waste memory.