I think it was the de.wikisource.org MediaWiki:Commons.js that fails because of a missing function and, so, stop execution of the others JavaScript scripts including the one that adds previous and next links.

I've fixed this issue using my global right in order to don't let the wiki broken anytime more: https://de.wikisource.org/w/index.php?title=MediaWiki%3ACommon.js&diff=2003222&oldid=1803972

I hope that anything works fine now.

Argh, mid-air collisions with Tpt. :)
Thanks for investigating this, I was also just about to investigate the case of "hasClass" not being found.

Tpt: Do you think it's likely that

• https://bugzilla.wikimedia.org/show_bug.cgi?id=48019
• https://bugzilla.wikimedia.org/show_bug.cgi?id=48182

have the same root problem and should receive the same fix?

(In reply to comment #2)
Yes, it's looks like it's the same error. The hasClass( DOMNode, class name ) function was maybe provided by an old MediaWiki JavaScript code that have been removed and so code that rely on it have been broken. I believe that my edit have fixed also bug 48182 and a similar change can fix bug 48019 .