Warning: Undefined global variable $wgContLang in /usr/share/mediawiki/extensions/Realnames/Realnames.body.php on line 254

Warning: Undefined global variable $wgContLang in /usr/share/mediawiki/extensions/Realnames/Realnames.body.php on line 254
MediaWiki internal error.

Original exception: [849867b8fc3b17a0b4a26971] /commissiewiki/index.php?title=Speciaal:Aanmelden&returnto=Hoofdpagina Error: Call to a member function getNsText() on null
Backtrace:
from /usr/share/mediawiki/extensions/Realnames/Realnames.body.php(257)
#0 /usr/share/mediawiki/extensions/Realnames/Realnames.body.php(406): ExtRealnames::getNamespacePrefixes()
#1 /usr/share/mediawiki/extensions/Realnames/Realnames.body.php(337): ExtRealnames::lookForBare()
#2 /usr/share/mediawiki/includes/HookContainer/HookContainer.php(338): ExtRealnames::hookBeforePageDisplay()
#3 /usr/share/mediawiki/includes/HookContainer/HookContainer.php(137): MediaWiki\HookContainer\HookContainer->callLegacyHook()
#4 /usr/share/mediawiki/includes/HookContainer/HookRunner.php(946): MediaWiki\HookContainer\HookContainer->run()
#5 /usr/share/mediawiki/includes/OutputPage.php(2871): MediaWiki\HookContainer\HookRunner->onBeforePageDisplay()
#6 /usr/share/mediawiki/includes/MediaWiki.php(922): OutputPage->output()
#7 /usr/share/mediawiki/includes/MediaWiki.php(562): MediaWiki->main()
#8 /usr/share/mediawiki/index.php(50): MediaWiki->run()
#9 /usr/share/mediawiki/index.php(46): wfIndexMain()
#10 {main}

Exception caught inside exception handler: [849867b8fc3b17a0b4a26971] /commissiewiki/index.php?title=Speciaal:Aanmelden&returnto=Hoofdpagina Error: Call to a member function getNsText() on null
Backtrace:
from /usr/share/mediawiki/extensions/Realnames/Realnames.body.php(257)
#0 /usr/share/mediawiki/extensions/Realnames/Realnames.body.php(406): ExtRealnames::getNamespacePrefixes()
#1 /usr/share/mediawiki/extensions/Realnames/Realnames.body.php(337): ExtRealnames::lookForBare()
#2 /usr/share/mediawiki/includes/HookContainer/HookContainer.php(338): ExtRealnames::hookBeforePageDisplay()
#3 /usr/share/mediawiki/includes/HookContainer/HookContainer.php(137): MediaWiki\HookContainer\HookContainer->callLegacyHook()
#4 /usr/share/mediawiki/includes/HookContainer/HookRunner.php(946): MediaWiki\HookContainer\HookContainer->run()
#5 /usr/share/mediawiki/includes/OutputPage.php(2871): MediaWiki\HookContainer\HookRunner->onBeforePageDisplay()
#6 /usr/share/mediawiki/includes/exception/MWExceptionRenderer.php(183): OutputPage->output()
#7 /usr/share/mediawiki/includes/exception/MWExceptionRenderer.php(102): MWExceptionRenderer::reportHTML()
#8 /usr/share/mediawiki/includes/exception/MWExceptionHandler.php(131): MWExceptionRenderer::output()
#9 /usr/share/mediawiki/includes/