So it's this line.

Malformed URIs occur when you run encodeURIComponent on something that cannot be encoded.

This is entirely possible, since we run it on user-provided data. Is there some specific solution to this?

In T271487#6730311, @Daimona wrote:

So it's this line.

Malformed URIs occur when you run encodeURIComponent on something that cannot be encoded.

This is entirely possible, since we run it on user-provided data. Is there some specific solution to this?

Just try/catch and discard nonsense, generally.

In T271487#6730323, @Jdforrester-WMF wrote:

Just try/catch and discard nonsense, generally.

Yeah, was keeping that as the last chance. But it seems acceptable after all.

In T271487#6730311, @Daimona wrote:

So it's this line.

Malformed URIs occur when you run encodeURIComponent on something that cannot be encoded.

FF83, Linux. I'm getting this error on every filter I try at enwiki, including https://en.wikipedia.org/wiki/Special:AbuseFilter/1014, which consists of entirely of false. Maybe there's something else going on here.

In T271487#6734827, @suffusion_of_yellow wrote:

In T271487#6730311, @Daimona wrote:

So it's this line.

Malformed URIs occur when you run encodeURIComponent on something that cannot be encoded.

FF83, Linux. I'm getting this error on every filter I try at enwiki, including https://en.wikipedia.org/wiki/Special:AbuseFilter/1014, which consists of entirely of false. Maybe there's something else going on here.

It seems you're right; it even errors out for empty filters. However, this is still working for me locally, so it must have something to do with the config of WMF wikis. I think it might be trying to use a non-initialized value or something like that, because if I manually run the relevant code in the console (without using workers):

xhr = new XMLHttpRequest();
xhr.open(
	'GET',
	mw.config.get( 'wgServer' ) + new mw.Api().defaults.ajax.url + '?action=abusefilterchecksyntax&format=json&filter=false',
	false
);
xhr.send();
xhr.responseText

I get, as expected,

"{"abusefilterchecksyntax":{"status":"ok"}}"

Also, before creating the request it checks whether mwapipath is falsey and bails if it is, so it means it's effectively getting a truly value. Which means, I believe, that exactly one of mw.config.get( 'wgServer' ) and new mw.Api().defaults.ajax.url is not returning the correct value, perhaps because it's called too early.

Further investigation to come later.

Change 655423 had a related patch set uploaded (by Daimona Eaytoy; owner: Daimona Eaytoy):
[mediawiki/extensions/AbuseFilter@master] Don't pass protocol-relative URLs to the Ace worker

https://gerrit.wikimedia.org/r/655423

Change 655423 merged by jenkins-bot:
[mediawiki/extensions/AbuseFilter@master] Don't pass protocol-relative URLs to the Ace worker

https://gerrit.wikimedia.org/r/655423

Change 655394 had a related patch set uploaded (by Jforrester; owner: Daimona Eaytoy):
[mediawiki/extensions/AbuseFilter@wmf/1.36.0-wmf.25] Don't pass protocol-relative URLs to the Ace worker

https://gerrit.wikimedia.org/r/655394

Change 655394 merged by jenkins-bot:
[mediawiki/extensions/AbuseFilter@wmf/1.36.0-wmf.25] Don't pass protocol-relative URLs to the Ace worker

https://gerrit.wikimedia.org/r/655394

Mentioned in SAL (#wikimedia-operations) [2021-01-12T21:50:39Z] <jforrester@deploy1001> Synchronized php-1.36.0-wmf.25/extensions/AbuseFilter/modules/mode-abusefilter.js: T271487 Don't pass protocol-relative URLs to the Ace worker (duration: 01m 06s)

Thanks @Jdforrester-WMF bit too early to tell, but silence at the far end of the graph usually a good sign.

The problem is gone for me on enwiki. And the Ace editor now warns me about invalid syntax. Thanks!