SpecialAdvancedTranslate (on translatewiki) fails to load as it cannot process the language code.

For e.g. https://translatewiki.net/w/i.php?language=sv&module=namespace&title=Special%3AAdvancedTranslate the following backtrace is returned:

#0 /www/translatewiki.net/w/languages/Language.php(4215): Language::getFileName(string, string, string)
#1 /www/translatewiki.net/w/extensions/Translate/ffs/MediaWikiComplexMessages.php(740): Language::getMessagesFileName(string)
#2 /www/translatewiki.net/w/extensions/Translate/specials/SpecialMagic.php(173): NamespaceCM->__construct(string)
#3 /www/translatewiki.net/w/includes/specialpage/SpecialPage.php(382): SpecialMagic->execute(NULL)
#4 /www/translatewiki.net/w/includes/specialpage/SpecialPageFactory.php(516): SpecialPage->run(NULL)
#5 /www/translatewiki.net/w/includes/MediaWiki.php(294): SpecialPageFactory::executePath(Title, RequestContext)
#6 /www/translatewiki.net/w/includes/MediaWiki.php(609): MediaWiki->performRequest()
#7 /www/translatewiki.net/w/includes/MediaWiki.php(458): MediaWiki->main()
#8 /www/translatewiki.net/w/index.php(46): MediaWiki->run()
#9 {main}

Reported on: https://translatewiki.net/wiki/Thread:Support/Special:AdvancedTranslate_not_opening_up_for_mr_language

Version: unspecified
Severity: normal