Exception when exporting document that contains links with an empty address.

Workaround:

private void Button_Click_1(object sender, RoutedEventArgs e)
{
    foreach (SpreadsheetHyperlink item in this.radSpreadsheet.Workbook.ActiveWorksheet.Hyperlinks.ToList())
    {
        if (string.IsNullOrEmpty(item.HyperlinkInfo.Address))
        {
            this.radSpreadsheet.Workbook.ActiveWorksheet.Hyperlinks.Remove(item);

        }
    }
    
}