解決Revit開發程序運行時，按ESC退出報錯問題

對特定的異常進行捕獲和報錯 

try
{
    var reference = uidoc.Selection.PickObject(ObjectType.Element, "請選擇您要查看的元素");
}
catch (Autodesk.Revit.Exceptions.OperationCanceledException ex)
{
    TaskDialog.Show("ERROR", "未選取任何對象！");
    //TaskDialog.Show("ERROR",ex.ToString());
    return Result.Failed;
}