Hi, testing out REL1_34, i'm getting:
[31-Oct-2019 15:08:23 UTC] PHP Fatal error: Uncaught InvalidArgumentException: Key "CanonicalNamespaceNames" not found in input sources in /srv/mediawiki/w/includes/config/ServiceOptions.php:52
Stack trace:
#0 /srv/mediawiki/w/includes/ServiceWiring.php(519): MediaWiki\Config\ServiceOptions->__construct(Array, Object(GlobalVarConfig))
#1 /srv/mediawiki/w/includes/libs/services/ServiceContainer.php(458): Wikimedia\Services\ServiceContainer->{closure}(Object(MediaWiki\MediaWikiServices))
#2 /srv/mediawiki/w/includes/libs/services/ServiceContainer.php(427): Wikimedia\Services\ServiceContainer->createService('NamespaceInfo')
#3 /srv/mediawiki/w/includes/MediaWikiServices.php(770): Wikimedia\Services\ServiceContainer->getService('NamespaceInfo')
#4 /srv/mediawiki/w/includes/MWNamespace.php(238): MediaWiki\MediaWikiServices->getNamespaceInfo()
#5 /srv/mediawiki/w/extensions/ArticleRatings/ArticleRatingsHooks.php(10): MWNamespace::getContentNamespaces()
#6 /srv/mediawiki/w/includes/registration/ExtensionRegistry.php(440): AreHooks::onRegisterExtension(Array)
in /srv/mediawiki/w/includes/config/ServiceOptions.php on line 52
Seems that ArticleRatings calls MWNamespace::getContentNamespaces().
php version: 7.3