Our error logging has flagged a bug in our code, relating to the aborting of API requests. It's unlikely to be user-facing and is rare but should be understood and addressed. The error hints that we are trying to cancel an API request relating to the display of a page preview that has already completed, meaning we may be showing page previews that are not meant to be displayed. Fixing the error will also reduce noise in our error logging allowing us to see more critical errors clearly.
https://logstash.wikimedia.org/app/kibana#/doc/logstash-*/logstash-2020.08.04/clienterror?id=AXO5iD43MQ_08tQaE0-T&_g=h@e3739c2
# Developer notes
Possibly all that's needed here is a check for the abort method being present before calling.
https://github.com/wikimedia/mediawiki-extensions-Popups/blob/e37ce8ef80e13b1755ccafbecbf1b0e46879113b/src/gateway/rest.js#L77