message: handle null as empty date and pass null to labelFunc instead of date
diff: @@ -57,7 +57,7 @@ export default class DateTextField extends PureComponent {
  const date = moment(value);
  if (labelFunc) {
  - return labelFunc(date, invalidLabel);
  + return labelFunc(isEmpty ? null : date, invalidLabel);
  }
  if (isEmpty) {
  