How do I add items from a datagridview to a shorping cart using buttoncolum for selection

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C#

I am trying to get data from datagridview to a list and i refer to the list as a shopping Cart. am using a buttonColumn inoder to get the data. The columns am targeting are ProductName and price i have tried a few ways but am having erros like this "Object reference not set to an instance of an object." i cant what exactly am missing please enlighten me

What I have tried:

private void ViewSearchData_CellContentClick(object sender, DataGridViewCellEventArgs e)
      {
          List<Items> Cart;

           if (e.ColumnIndex==ViewSearchData.Columns["SELECTED"].Index)
           {

           }

              String name = ViewSearchData.Rows[e.RowIndex].Cells["name"].Value.ToString();
              int price = (int)(ViewSearchData.Rows[e.RowIndex].Cells["price"].Value);
              Items item = new Items(name, price);
              Cart = new List<Items>();
              Cart.Add(item);

      }