绑定到gridview时出现null引用异常

Question

在将数据源（可能为空，具体取决于具体情况）绑定到gridview时，我得到一个nullreference异常。我该如何解决这个问题？

if (!IsPostBack)
{
    SetGridView();
}

private void SetGridView()
{
    GroupTelephoneNumberManagementGridView.DataSourceID = odsGroupTelephoneNumbers.ID;
    GroupTelephoneNumberManagementGridView.DataBind();
}

protected void GroupTelephoneNumberManagementGridView_DataBound(object sender, EventArgs e)
{
    var gridView = (GridView)sender;
    gridView.BottomPagerRow.Visible = true;
}

protected void GroupTelephoneNumberManagementGridView_RowDataBound(object sender, GridViewRowEventArgs e)
        {
            //Check for the row type, which should be data row
            if (e.Row.RowType == DataControlRowType.DataRow)
            {
                var groupPhoneNumber = (GroupPhonenumber)e.Row.DataItem;
                var activateTelephoneOption = (RadioButtonList)e.Row.FindControl("activateTelephoneOption");

                //Set a unique value as data-attribute in RadioButtonList
                activateTelephoneOption.Attributes.Add(DataTelephonenumber, groupPhoneNumber.Phonenumber);
                activateTelephoneOption.Attributes.Add(DataUserId, groupPhoneNumber.UserId);

                //fill the name column in the gridview with firstname and lastname
                var nameLabel = (Label)e.Row.FindControl("nameLabel");
                nameLabel.Text = groupPhoneNumber.FirstName + " " + groupPhoneNumber.LastName;

                //Get if the number is activated or not 
                activateTelephoneOption.SelectedIndex = groupPhoneNumber.Activated ? 1 : 0;

                // Remove the landcode form the phonenumber
                var numberLabel = (Label)e.Row.FindControl("numberLabel");
                numberLabel.Text = PhoneNumberWithoutlandCode(groupPhoneNumber.Phonenumber);
            }
        }

注意：这已经生效并且正常工作，但在某些情况下，数据源应为null，因为客户没有要绑定的任何数字。 （在那种情况下，我得到一个空引用异常，所有其他情况完美地工作）。