MediaWiki version: 1.35.0-wmf.20
Argument 2 passed to MediaWiki\Extension\AbuseFilter\VariableGenerator\RunVariableGenerator::getStashEditVars() must be of the type string, null given, called in /srv/mediawiki/php-1.35.0-wmf.20/extensions/AbuseFilter/includes/AbuseFilterHooks.php on line 820
Unsure. Since it happens in a deferred update during edit stashing, it may just cause the edit not to be stashed, without the user knowing. Seen 6 times in the last 24h.
It complains about the summary being null. However, the summary is given by the ParserOutputStashForEdit hook, which is only documented to pass strings. IMHO it should be fixed in core, and it shouldn't pass null. If the summary is empty, passing an empty string seems more reasonable. Downstream (in the hook handler), we should add typehints.