我只是将Mediawiki与皮肤一起使用，但无法访问Special：Preferences 错误日志

MWException from line 193 of /var/www/wiki/includes/preferences/DefaultPreferencesFactory.php: Global Default '' is invalid for field liberty-dark

Backtrace:

#0 /var/www/wiki/includes/preferences/DefaultPreferencesFactory.php(143): MediaWiki\Preferences\DefaultPreferencesFactory->loadPreferenceValues(User,RequestContext,array)
#1 /var/www/wiki/includes/preferences/DefaultPreferencesFactory.php(1419): MediaWiki\Preferences\DefaultPreferencesFactory->getFormDescriptor(User,RequestContext)
#2 /var/www/wiki/includes/specials/SpecialPreferences.php(129): MediaWiki\Preferences\DefaultPreferencesFactory->getForm(User,RequestContext)
#3 /var/www/wiki/includes/specials/SpecialPreferences.php(86): SpecialPreferences->getFormObject(User,RequestContext)
#4 /var/www/wiki/includes/specialpage/SpecialPage.php(565): SpecialPreferences->execute(NULL)
#5 /var/www/wiki/includes/specialpage/SpecialPageFactory.php(568): SpecialPage->run(NULL)
#6 /var/www/wiki/includes/MediaWiki.php(288): SpecialPageFactory::executePath(Title,RequestContext)
#7 /var/www/wiki/includes/MediaWiki.php(861): MediaWiki->performRequest()
#8 /var/www/wiki/includes/MediaWiki.php(524): MediaWiki->main()
#9 /var/www/wiki/index.php(42): MediaWiki->run()
#10 {main}

Mediawiki版本：1.31.6
和皮肤我用于mediawiki的内容 https://gitlab.com/librewiki/Liberty-MW-Skin/tree/REL1_31