Visit https://www.mediawiki.org/wiki/Talk:Sandbox, open your browser's development tools > Net panel, then mouse over the links in the informational header.

Notice that popups makes API requests to query extracts|pageimages|revisions|info for these hyperlinks. But the titles parameter is empty, so obviously the API returns nothing.

resources/ext.popups.renderer.article.js should return early if link.data( 'title' ) is empty. And if there's no data('title') then article.init() shouldn't be called in the first place. It seems mw.popups.selectPopupElements() is trying to filter out blank titles.

Version: master
Severity: normal