Spotted in the REL1_35 branch, on PHP 8.1 - not spotted previously on PHP 7.4.
MediaWiki internal error. Original exception: [d9ae8e50de3225aa0a9be7b4] /wiki/Strike_Back_Wiki Error from line 329 of /var/www/production/w/includes/HookContainer/HookContainer.php: Non-static method SkinMonaco::onOutputPageBodyAttributes() cannot be called statically Backtrace: #0 /var/www/production/w/includes/HookContainer/HookContainer.php(132): MediaWiki\HookContainer\HookContainer->callLegacyHook() #1 /var/www/production/w/includes/HookContainer/HookRunner.php(2740): MediaWiki\HookContainer\HookContainer->run() #2 /var/www/production/w/includes/OutputPage.php(3147): MediaWiki\HookContainer\HookRunner->onOutputPageBodyAttributes() #3 /var/www/production/w/includes/skins/SkinTemplate.php(405): OutputPage->headElement() #4 /var/www/production/w/includes/skins/SkinTemplate.php(127): SkinTemplate->prepareQuickTemplate() #5 /var/www/production/w/includes/skins/SkinTemplate.php(144): SkinTemplate->generateHTML() #6 /var/www/production/w/includes/OutputPage.php(2622): SkinTemplate->outputPage() #7 /var/www/production/w/includes/MediaWiki.php(954): OutputPage->output() #8 /var/www/production/w/includes/MediaWiki.php(967): MediaWiki->{closure}() #9 /var/www/production/w/includes/MediaWiki.php(547): MediaWiki->main() #10 /var/www/production/w/index.php(53): MediaWiki->run() #11 /var/www/production/w/index.php(46): wfIndexMain() #12 {main}