Fix for onEmptyFilter getting stuck on internal datasource filters.

[deanhannigan]

Description

The onEmptyFilter filter gets stuck in the filter list when all filter fields are removed. If you had previously set this filter to none it will cause the filter to always return zero rows. The only way to get around it is to refresh or add in fields to make the onEmptyFilter UI visible again.

Addresses

Clears the onEmptyFilter when all field filters have been removed. This ensures that all rows continue to be returned when no fields are specified.

Steps

1. Pick an internal datasource in the Data section and open the filter menu
2. Add a field to the search and the change the When filter empty to Return no rows
3. Remove the field entry and save the filter.
4. Despite all field filters being removed and the When filter empty option being hidden, the onEmptyFilter is still present in the filter UX and will cause no rows to appear.

The same behaviour can be seen when filtering datasources on components in the builder.

Screenshots

Launchcontrol

Minor fix to ensure onEmptyFilter is cleared from datasource filters when no fields are specified.