The summary endpoint produced an unknown page type, "standard", and no extract for today's enwiki featured article, "Vultee Vengeance in Australian service".
Replicate locally by accessing the specific revision: http://0.0.0.0:6927/en.wikipedia.org/v1/page/summary/Vultee_Vengeance_in_Australian_service/848656723
The response is as follows:
// https://en.wikipedia.org/api/rest_v1/page/summary/Vultee_Vengeance_in_Australian_service { "type": "standard", "title": "Vultee Vengeance in Australian service", "displaytitle": "Vultee Vengeance in Australian service", "namespace": { "id": 0, "text": "" }, "titles": { "canonical": "Vultee_Vengeance_in_Australian_service", "normalized": "Vultee Vengeance in Australian service", "display": "Vultee Vengeance in Australian service" }, "pageid": 53771831, "thumbnail": { "source": "https://upload.wikimedia.org/wikipedia/commons/thumb/c/c5/No_12_Squadron_Vengeance_dive_bomber_in_flight_during_December_1943.JPG/320px-No_12_Squadron_Vengeance_dive_bomber_in_flight_during_December_1943.JPG", "width": 320, "height": 241 }, "originalimage": { "source": "https://upload.wikimedia.org/wikipedia/commons/c/c5/No_12_Squadron_Vengeance_dive_bomber_in_flight_during_December_1943.JPG", "width": 460, "height": 347 }, "lang": "en", "dir": "ltr", "revision": "848656723", "tid": "df321e1c-7eb6-11e8-bf5b-2aeaebe33987", "timestamp": "2018-07-03T11:47:28Z", "content_urls": { "desktop": { "page": "https://en.wikipedia.org/wiki/Vultee_Vengeance_in_Australian_service", "revisions": "https://en.wikipedia.org/wiki/Vultee_Vengeance_in_Australian_service?action=history", "edit": "https://en.wikipedia.org/wiki/Vultee_Vengeance_in_Australian_service?action=edit", "talk": "https://en.wikipedia.org/wiki/Talk:Vultee_Vengeance_in_Australian_service" }, "mobile": { "page": "https://en.m.wikipedia.org/wiki/Vultee_Vengeance_in_Australian_service", "revisions": "https://en.m.wikipedia.org/wiki/Special:History/Vultee_Vengeance_in_Australian_service", "edit": "https://en.m.wikipedia.org/wiki/Vultee_Vengeance_in_Australian_service?action=edit", "talk": "https://en.m.wikipedia.org/wiki/Talk:Vultee_Vengeance_in_Australian_service" } }, "api_urls": { "summary": "https://en.wikipedia.org/api/rest_v1/page/summary/Vultee_Vengeance_in_Australian_service", "metadata": "https://en.wikipedia.org/api/rest_v1/page/metadata/Vultee_Vengeance_in_Australian_service", "references": "https://en.wikipedia.org/api/rest_v1/page/references/Vultee_Vengeance_in_Australian_service", "media": "https://en.wikipedia.org/api/rest_v1/page/media/Vultee_Vengeance_in_Australian_service", "edit_html": "https://en.wikipedia.org/api/rest_v1/page/html/Vultee_Vengeance_in_Australian_service", "talk_page_html": "https://en.wikipedia.org/api/rest_v1/page/html/Talk:Vultee_Vengeance_in_Australian_service" }, "extract": "", "extract_html": "" }
Popups only understands:
const previewTypes = { /** empty preview */ TYPE_GENERIC: 'generic', /** standard preview */ TYPE_PAGE: 'page', /** disambiguation preview */ TYPE_DISAMBIGUATION: 'disambiguation' };
And only defaults to TYPE_PAGE when an extract exists.
Developer notes
extractLeadIntroduction is returning an empty string. Input looks like this:
<html><head></head><body><p><span> </span> </p> <p about="#mwt4">|} The <a href="./Royal_Australian_Air_Force" title="Royal Australian Air Force">Royal Australian Air Force</a> (RAAF) operated <a href="./Vultee_A-31_Vengeance" title="Vultee A-31 Vengeance">Vultee Vengeance</a> <a href="./Dive_bomber" title="Dive bomber">dive bombers</a> during <a href="./World_War_II" title="World War II">World War II</a>. The Australian Government ordered 297 of the type in late 1941 as part of efforts to expand the RAAF. This order was later increased to 400 aircraft. A few Vengeances arrived in Australia during 1942, and large-scale deliveries commenced in early 1943; further orders were cancelled in 1944 after 342 had been delivered. The RAAF was slow to bring its Vengeances into service, their first combat missions being flown in June 1943. The main deployment of the type took place between mid-January and early March 1944, when <a href="./Squadron_(aviation)" title="Squadron (aviation)">squadrons</a> operated in support of Australian and United States Army forces in New Guinea. This force was withdrawn after only six weeks as the Vengeance was considered inferior to other aircraft available to the Allied air forces. All of the RAAF's five Vengeance-equipped squadrons were re-equipped with <a href="./Consolidated_B-24_Liberator" title="Consolidated B-24 Liberator">Consolidated B-24 Liberator</a> heavy bombers. Vengeances continued to be used in training and support roles with the RAAF until 1946, and some were transferred to the <a href="./Royal_Australian_Navy" title="Royal Australian Navy">Royal Australian Navy</a> between 1948 and 1950 for ground training. Historians' assessments of the Vengeance's career in Australian service differ. While there is consensus that the type was obsolete, some argue that it nevertheless proved successful. Others, including the RAAF's Air Power Development Centre, have judged that the Vengeance's performance was mixed and the type was not suited to Australia's requirements.</p></body></html>
node.querySelector('b') returns undefined as there are no child nodes of the lead that are b tags.
This seems to be an intentional check added in T186847, which seems a little misguided and Wikimedia wiki specific as it means if a paragraph has no bold tag inside the lead, the lead and thus the summary will always be empty.