displayDialogAsync for ExportData doesn't throw any error when the Viz is a Dashboard

[florent-guinard]

When the current embedded Viz is a Dashboard and no Worksheet is selected the Download > Data button in the tooltip is greyed out:

Calling the displayDialogAsync(TableauDialogType.ExportData) function on this Viz doesn't display any dialog (since the Data button is greyed out) but doesn't throw any error either: would it be possible to throw an exception in this case so that we can warn our users that are expecting a dialog to be opened?