Ошибка NullReferenceException после Observablecollection clear

Question

После обновления БД через метод Clear(); производиться обновление Observablecollection и DataGrid. Также опустошаются TextBoxes. Пока все хорошо. Однако после заполенения TextBox и попытки заново добавить данные в БД выдается ошибка NullReferenceException

public class Games: INotifyPropertyChanged
    {

    public event PropertyChangedEventHandler PropertyChanged;
    public void OnPropertyChanged([CallerMemberName]string prop = "")
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(prop));
        }
    }

        private string name;
        public string Name
        {
            get { return name; }
            set
            {
                name = value;
                OnPropertyChanged();
            }
        }

        private string price;
        public string Price
        {
            get { return price; }
            set
            {
                price = value;
                OnPropertyChanged();
            }
        }
    }

public class GamesVM
{
    public GamesVM()
    {
        GamesCollection = new ObservableCollection<Games>();
        _SelectedGames = new Games();
        SearchGames();
    }

    public ObservableCollection<Games> GamesCollection { get; set; }

    private Games _SelectedGames;
    public Games SelectedGames
    {
       get
       { return _SelectedGames; }
       set
       { _SelectedGames = value; }
    }

    public void SearchGames()
        {
            string query = "SELECT * FROM GamesTable";
            command = new MySqlCommand(query, connection);
            adapter = new MySqlDataAdapter(command);
            DataTable dt = new DataTable();
            adapter.Fill(dt);

            foreach (DataRow row in dt.Rows)
            {
                var game = new Games
                {
                    Name = row["Name"].ToString(),
                    Price= row["Price"].ToString()
                };
                GamesCollection.Add(game);
            }
        }

    public void InsertNewGame()
    {
       if(SelectedGames.Name != null)
       {
       string Insert = "INSERT INTO Games (Name, Price) VALUES (SelectedGames.Name, SelectedGames.Price)";
       }
/// <summary>
/// ... 
/// </summary>
    }

   publick void Clear()
   {
      GamesCollection.Clear();
      SearchGames();
   }
}