page_image is currently always set and added to the page_props table, even if there is no relevant image. Instead of not adding the property, the property is added with a blank value.
e.g. for https://www.wikidata.org/wiki/Q5160
select * from page_props where pp_page = 6102; +---------+--------------+------------------------------------------------------------------------------------------------------------------------------------------+------------+ | pp_page | pp_propname | pp_value | pp_sortkey | +---------+--------------+------------------------------------------------------------------------------------------------------------------------------------------+------------+ | 6102 | displaytitle | <span class="wikibase-title "> <span class="wikibase-title-label">'Are'are</span> <span class="wikibase-title-id">(Q5160)</span> </span> | NULL | | 6102 | page_image | | NULL | | 6102 | wb-claims | 7 | 7 | | 6102 | wb-sitelinks | 6 | 6 | +---------+--------------+------------------------------------------------------------------------------------------------------------------------------------------+------------+ 4 rows in set (0.00 sec)
we should instead should just not set the page_image property in the ParserOutput in this case. This is how it is done for wikitext pages.