🐛 pass loc as a string to location service

Without passing a string, we get an error when based_near is nil. This was discovered when testing Bulkrax in a valkyrized app. When based_near is nil, Hyrax will create a new controlled vocab location object, which gets passed off to a lookup that failed in the #extract_id method.

app/indexers/concerns/hyrax/location_indexer.rb

@@ -14,7 +14,7 @@ def to_solr
 
     def based_near_label_lookup(locations)
       locations.map do |loc|
-        location_service.full_label(loc)
+        location_service.full_label(loc.to_s)
       end
     end