Hi, im seeing this in the logs for mw 1.31 running php 7.2, we use CentralAuth.
```
InvalidArgumentException from line 1512 of /srv/mediawiki/w/includes/Block.php: Blocker must be a local user or a name that cannot be a local user
#0 /srv/mediawiki/w/includes/Block.php(461): Block->setBlocker(User)
#1 /srv/mediawiki/w/includes/Block.php(492): Block->initFromRow(stdClass)
#2 /srv/mediawiki/w/includes/Block.php(362): Block::newFromRow(stdClass)
#3 /srv/mediawiki/w/includes/Block.php(1195): Block->newLoad(NULL)
#4 /srv/mediawiki/w/includes/page/Article.php(768): Block::newFromTarget(string, NULL)
#5 /srv/mediawiki/w/includes/page/Article.php(667): Article->getRobotPolicy(string, ParserOutput)
#6 /srv/mediawiki/w/includes/actions/ViewAction.php(68): Article->view()
#7 /srv/mediawiki/w/includes/MediaWiki.php(500): ViewAction->show()
#8 /srv/mediawiki/w/includes/MediaWiki.php(294): MediaWiki->performAction(Article, Title)
#9 /srv/mediawiki/w/includes/MediaWiki.php(861): MediaWiki->performRequest()
#10 /srv/mediawiki/w/includes/MediaWiki.php(524): MediaWiki->main()
#11 /srv/mediawiki/w/index.php(42): MediaWiki->run()
#12 {main}
```