note: on Aug 9th 1.41.0-wmf.20 was the active wiki version.

Would imply that the jquery.textSelection module isn't loaded, I guess? (Which it should be -- it's a dependency of the package that contains ext.wikiEditor.js) Or perhaps that somehow context.$textarea isn't actually a jQuery object -- it's created via $(this) in the initializer, but it's also stored in data wikiEditor-context where something could modify it.

Anyway, can't reproduce it on https://en.wikipedia.org/w/index.php?title=Wikipedia:Sandbox&action=edit. If you have the logstash link to the error that would be helpful for digging in to it.

CC @Samwilson as may be related to Comm Tech work.

I too struggle to see the codepath that causes this to happen. I can't see any gadgets modifying wikiEditor-context, and the $textarea property should always be set. There have been some changes to jquery.textSelection, so maybe in some circumstances it is silently failing to load completely?

@DLynch Here is the logstash error. It has a custom label of WikiEditor:T343940

I looked at a more-complete stack trace (on this specific error):

at jquery.wikiEditor.js/$.fn.wikiEditor https://en.wikipedia.org/w/load.php?lang=en&modules=ext.wikiEditor&skin=vector&version=13m6h:19:82
at ext.wikiEditor.js/mw.addWikiEditor https://en.wikipedia.org/w/load.php?lang=en&modules=ext.wikiEditor&skin=vector&version=13m6h:4:695
at ext.wikiEditor.js/< https://en.wikipedia.org/w/load.php?lang=en&modules=ext.wikiEditor&skin=vector&version=13m6h:4:574
at e https://code.jquery.com/jquery-3.5.1.min.js:2:30005
at Deferred/then/l/</t< https://code.jquery.com/jquery-3.5.1.min.js:2:30307

...so, I think this likely is a gadget or userscript doing something unwise. There's no reason for that external jQuery to be loaded unless someone is doing something strange, and if you're already loading external-jquery then you might well be hard-embedding other things without fetching their dependencies...

Global search suggests that there's only one place that that particular version of external jquery is being called, added in November 2022.

There are a bunch of other people loading different versions of jQuery.

Notified that specific user: https://en.wikipedia.org/wiki/User_talk:IJohnKennady#Javascript_errors

I've checked the remaining matches in global search. Most are actually commented references. There are full html pages but these won't trigger such problems. Remaining are either properly guarded on the jQuery variable or the user isn't active any longer.

The only one that gives me some concern is https://fi.wikipedia.org/wiki/Käyttäjä:Kulmalukko/monobook.js But possibly the user switched skins and this is not in use either ? Still we might want to inform that user specifically

In T343940#9112469, @TheDJ wrote:

Notified that specific user: https://en.wikipedia.org/wiki/User_talk:IJohnKennady#Javascript_errors

I've removed the offending line.

In T343940#9112526, @TheDJ wrote:

The only one that gives me some concern is https://fi.wikipedia.org/wiki/Käyttäjä:Kulmalukko/monobook.js

Removed.