@nursix  We are returning False from fulltext() function and we also need it, when solr is disabled or unavailable in those cases.
If suppose i return None in fulltext() function when solr is unavailabe - then  for this ((S3FieldSelector("~.name").text("test")) | (S3FieldSelector("~.document.file").text("test")) 
the query will whole become None
But the expected output we would want is : (project_project.name like "*test*")
So, I had kept the above condition.