some steps to reproduce:
1. get ezFind working

2. customize some class for search:

• at any class (article is good), add an attribute named "extrasolrfield" of type textline, and mark it searchable
• create a new object of that class, insert in the "extrasolrfield" some sentence with a "relavant" word for search. with the typo, to make the word unique and save work later
• search it in front end, just to assure there is a single object as result

3. customize ezsearch template:

• open the ezfind/design/ezdemo/templates/search.tpl file
• modify the fetch operator to include the field.
  it becomes:

      {set $search=fetch( ezfind,search,
                          hash( 'query', $search_text,
                                'offset', $view_parameters.offset,
                                'limit', $page_limit,
                                'sort_by', hash( 'score', 'desc' ),
                                'facet', $defaultSearchFacets,
                                'as_objects', false(),
                                'fields_to_return', array( 'attr_extrasolrfield_s'),
                                'filter', $filterParameters,
                                'publish_date', $dateFilter,
                                'spell_check', array( true() ),
                                'search_result_clustering', hash( 'clustering', false() ) )
                               )}
      {$search|dump('show',4)}
  

  note: the option "asObjects" is incorrect, it needs also to be modified to "as_objects"

5. run test:

• in frontend, search for the "relavant" word that should give 1 result
• check in the dump result that the array "fields" is not present as expected.

the "fields" should be included, according to comment in eZSolr::buildResultObjects():

                        // check if field is not in the explicit field list, to keep explode from generating notices.
                        // it may be a field originating from the explicit fieldlist to return, so it should be added for template consumption
                        // note that the fieldname will be kept verbatim in a substructure 'fields'