public void ConfigureServices(IServiceCollection services)
{
            services.AddRazorPages();
            services.AddServerSideBlazor();

            services.AddHttpContextAccessor();
            services.AddSingleton<AppState>();

            // More services
}

private HttpContextAccessor _httpContextAccessor;

public AppState(HttpContextAccessor httpContextAccessor)
{
     _httpContextAccessor = httpContextAccessor;
}