tooltips don't show now if null or undefined
tooltips don't show now if null or undefined

seanlandsman/ag-grid,makinggoodsoftware/ag-grid,ceolter/ag-grid,ceolter/angular-grid,ua9msn/ag-grid,killyosaur/ag-grid,seanlandsman/ag-grid,ceolter/ag-grid,ceolter/angular-grid,makinggoodsoftware/ag-grid,killyosaur/ag-grid,seanlandsman/ag-grid,ua9msn/ag-grid,killyosaur/ag-grid