public MainPageViewModel(IClientDataService clientDataService,
INavigationService navigationService)
{
_clientDataService = clientDataService ?? throw new ArgumentNullException(nameof(clientDataService));
_navigationService = navigationService ?? throw new ArgumentNullException(nameof(navigationService));
Title = "Clients";
BeginText = "Dit is een test text";
Clients = _clientDataService.GetClients(Config.Username);
NavigateClientCommand = new Command <Client>(async(client) => await NavigateToClient(client));
}