In betalabs the following error page is displayed (also more info on the error in logstash-beta.wmflabs.org) :
MediaWiki internal error.
Original exception: [WCplBgpEE4AAADraPfwAAAAK] /wiki/Talk:ET70 MWException from line 176 of /srv/mediawiki/php-master/includes/Hooks.php: Invalid callback CodeEditorHooks::onBeforePageDisplay in hooks for BeforePageDisplay
Backtrace:
#0 /srv/mediawiki/php-master/includes/OutputPage.php(2333): Hooks::run(string, array)
#1 /srv/mediawiki/php-master/includes/MediaWiki.php(858): OutputPage->output(boolean)
#2 /srv/mediawiki/php-master/includes/MediaWiki.php(870): Closure$MediaWiki::main()
#3 /srv/mediawiki/php-master/includes/MediaWiki.php(512): MediaWiki->main()
#4 /srv/mediawiki/php-master/index.php(43): MediaWiki->run()
#5 /srv/mediawiki/w/index.php(3): include(string)
#6 {main}
Exception caught inside exception handler: [WCplBgpEE4AAADraPfwAAAAK] /wiki/Talk:ET70 MWException from line 176 of /srv/mediawiki/php-master/includes/Hooks.php: Invalid callback CodeEditorHooks::onBeforePageDisplay in hooks for BeforePageDisplay
Backtrace:
#0 /srv/mediawiki/php-master/includes/OutputPage.php(2333): Hooks::run(string, array)
#1 /srv/mediawiki/php-master/includes/exception/MWException.php(174): OutputPage->output()
#2 /srv/mediawiki/php-master/includes/exception/MWException.php(220): MWException->reportHTML()
#3 /srv/mediawiki/php-master/includes/exception/MWExceptionHandler.php(69): MWException->report()
#4 /srv/mediawiki/php-master/includes/exception/MWExceptionHandler.php(137): MWExceptionHandler::report(MWException)
#5 /srv/mediawiki/php-master/includes/MediaWiki.php(540): MWExceptionHandler::handleException(MWException)
#6 /srv/mediawiki/php-master/index.php(43): MediaWiki->run()
#7 /srv/mediawiki/w/index.php(3): include(string)
#8 {main}