getActiveFilters is passing zeros when filters are not active

Articles filters in back-end are opened all the time, even if no search is performed. The filter status (show or hide) is detected in /layouts/joomla/searchtools/default.php from $data['view']->activeFilters.

It appeared that even when filters are empty 2 values are passed to activeFilters:
level=0
access=0

When this fix is applied the search filter is hidden until it's opened and an option is selected.