TableSorter empty column problem

Hi,

I am using Generic TableSorter class.When there is empty column in the table and if i click the column header(to Sort or accidentaly pressed) it is crashing.

How can i solve this problem.I thought of checking in the onActionSort method if the column is empty and then decide to execute the satement

wdContext.currentContextElement().getTableSorter().sort(wdEvent, wdContext.nodeCustomer());

But i dont know how to check if the column is empty ?.May be some of you might know how to solve this in better way than mine.All your help is appreciated.

Thanks