Delphi: smoothly manage a TDBGrid error (#20897)

say you have an active DBGrid, attached to a TDataset thru a TDatasource. Say the dataset has N not null fields. If the user forgets to insert one of the not null fields or if the user moves to a different row of the grid (implict post) before entering all not null fields, an ugly error message is shown at screen (see [login to view URL]). How can I smoothly handle the error ?