Sometimes, a BadMethodCallException arises on Special:ConstraintReport, and sometimes doesn't, even for the same entity. The example below corresponds to Q42.
[WvDWHApAIDAAAEhNrKYAAAAQ] 2018-05-07 22:41:50: Fatal exception of type "BadMethodCallException"
More information from logstash:
Call to a member function getMessageKey() on a non-object (null)
/srv/mediawiki/php-1.32.0-wmf.2/extensions/WikibaseQualityConstraints/src/ConstraintCheck/Helper/LoggingHelper.php:107
#0 /srv/mediawiki/php-1.32.0-wmf.2/extensions/WikibaseQualityConstraints/src/ConstraintCheck/DelegatingConstraintChecker.php(595): WikibaseQuality\ConstraintReport\ConstraintCheck\Helper\LoggingHelper->logConstraintCheck(WikibaseQuality\ConstraintReport\ConstraintCheck\Context\MainSnakContext, WikibaseQuality\ConstraintReport\Constraint, WikibaseQuality\ConstraintReport\ConstraintCheck\Result\CheckResult, string, double, string)
#1 /srv/mediawiki/php-1.32.0-wmf.2/extensions/WikibaseQualityConstraints/src/ConstraintCheck/DelegatingConstraintChecker.php(447): WikibaseQuality\ConstraintReport\ConstraintCheck\DelegatingConstraintChecker->getCheckResultFor(WikibaseQuality\ConstraintReport\ConstraintCheck\Context\MainSnakContext, WikibaseQuality\ConstraintReport\Constraint)
#2 /srv/mediawiki/php-1.32.0-wmf.2/extensions/WikibaseQualityConstraints/src/ConstraintCheck/DelegatingConstraintChecker.php(362): WikibaseQuality\ConstraintReport\ConstraintCheck\DelegatingConstraintChecker->checkConstraintsForMainSnak(Wikibase\DataModel\Entity\Item, Wikibase\DataModel\Statement\Statement, NULL, NULL)
#3 /srv/mediawiki/php-1.32.0-wmf.2/extensions/WikibaseQualityConstraints/src/ConstraintCheck/DelegatingConstraintChecker.php(334): WikibaseQuality\ConstraintReport\ConstraintCheck\DelegatingConstraintChecker->checkStatement(Wikibase\DataModel\Entity\Item, Wikibase\DataModel\Statement\Statement, NULL, NULL)
#4 /srv/mediawiki/php-1.32.0-wmf.2/extensions/WikibaseQualityConstraints/src/ConstraintCheck/DelegatingConstraintChecker.php(154): WikibaseQuality\ConstraintReport\ConstraintCheck\DelegatingConstraintChecker->checkEveryStatement(Wikibase\DataModel\Entity\Item, NULL, NULL)
#5 /srv/mediawiki/php-1.32.0-wmf.2/extensions/WikibaseQualityConstraints/src/Specials/SpecialConstraintReport.php(266): WikibaseQuality\ConstraintReport\ConstraintCheck\DelegatingConstraintChecker->checkAgainstConstraintsOnEntityId(Wikibase\DataModel\Entity\ItemId)
#6 /srv/mediawiki/php-1.32.0-wmf.2/includes/specialpage/SpecialPage.php(522): WikibaseQuality\ConstraintReport\Specials\SpecialConstraintReport->execute(string)
#7 /srv/mediawiki/php-1.32.0-wmf.2/includes/specialpage/SpecialPageFactory.php(568): SpecialPage->run(string)
#8 /srv/mediawiki/php-1.32.0-wmf.2/includes/MediaWiki.php(288): SpecialPageFactory::executePath(Title, RequestContext)
#9 /srv/mediawiki/php-1.32.0-wmf.2/includes/MediaWiki.php(861): MediaWiki->performRequest()
#10 /srv/mediawiki/php-1.32.0-wmf.2/includes/MediaWiki.php(524): MediaWiki->main()
#11 /srv/mediawiki/php-1.32.0-wmf.2/index.php(42): MediaWiki->run()
#12 /srv/mediawiki/w/index.php(3): include(string)
#13 {main}