Login Flow with shell

 An item with the same key has already been added. Key: 0'

public partial class LoginPageViewModel

    [ObservableProperty]
    bool isPopOpen;

    [ObservableProperty]
    User user = new();

    [RelayCommand]
    void OpenPopUp() {
        IsPopOpen = true;
    }

    [RelayCommand]
    async Task Login() {

        IsBusy = true;

        //var user = await authenticationService.LoginWithEmailAndPassword(User.Email!, User.Password!);
        //var user = await authenticationService.LoginWithEmailAndPassword("[email protected]", "123456");

        await appService.NavigateTo($"{nameof(NewLecturePage)}");

  <ShellContent
      ContentTemplate="{DataTemplate pages:LoginPage}"
      Route="loginPage"
      Shell.FlyoutBehavior="Disabled"
      Shell.FlyoutItemIsVisible="False" />

  <FlyoutItem>
      <ShellContent
          ContentTemplate="{DataTemplate pages:NewLecturePage}"
          Route="NewLecturePage" />
  </FlyoutItem>

public class StartupPageViewModel : BaseViewModel {

    private readonly IAppService _appService;
    private readonly IConnectivity _connectivity;

    public StartupPageViewModel(IAppService appService, IConnectivity connectivity) {

        _appService = appService;
        _connectivity = connectivity;

        CheckInternet(_connectivity.NetworkAccess);

    }

    private void CheckInternet(NetworkAccess networkAccess) {
        if(networkAccess is not NetworkAccess.Internet) {
            _appService.NavigateTo($"{nameof(NoInternetPage)}");
        } else {
            _appService.NavigateTo($"{nameof(LoginPage)}");
        }
    }
}