Fix: no search results found on documentation homepage
Fix: no search results found on documentation homepage

On the homepage there are no searchedEntities nor searchedVersions
defined, so the searchForm creates empty hiddenfields. PerformSeach
creates subqueries for thes empty values resulting in the return of an
'Empty' query object.

Solution: do not create these fields when there are no entities/versions

silverstripe/silverstripe-docsviewer,camfindlay/silverstripe-docsviewer,camfindlay/silverstripe-docsviewer,silverstripe/silverstripe-docsviewer,dhensby/silverstripe-docsviewer,dhensby/silverstripe-docsviewer