As a logged in user, http://newsletter-test.wmflabs.org/wiki/Special:Preferences gives an Internal error. Without accessing preferences, Echo notifications cannot be set, and therefore T101505 cannot be properly tested.
Reported initially at T76199#1393734
```
Internal error
[d48799a2] /wiki/Special:Preferences MWException from line 182 of /srv/vagrant/mediawiki/includes/Hooks.php: Invalid callback NewsletterHooks::onGetPreferences in hooks for GetPreferences
Backtrace:
#0 /srv/vagrant/mediawiki/includes/Preferences.php(99): Hooks::run(string, array)
#1 /srv/vagrant/mediawiki/includes/Preferences.php(1260): Preferences::getPreferences(User, RequestContext)
#2 /srv/vagrant/mediawiki/includes/specials/SpecialPreferences.php(60): Preferences::getFormObject(User, RequestContext)
#3 /srv/vagrant/mediawiki/includes/specialpage/SpecialPage.php(384): SpecialPreferences->execute(NULL)
#4 /srv/vagrant/mediawiki/includes/specialpage/SpecialPageFactory.php(581): SpecialPage->run(NULL)
#5 /srv/vagrant/mediawiki/includes/MediaWiki.php(285): SpecialPageFactory::executePath(Title, RequestContext)
#6 /srv/vagrant/mediawiki/includes/MediaWiki.php(634): MediaWiki->performRequest()
#7 /srv/vagrant/mediawiki/includes/MediaWiki.php(431): MediaWiki->main()
#8 /srv/vagrant/mediawiki/index.php(41): MediaWiki->run()
#9 /var/www/w/index.php(5): include(string)
#10 {main}
```