Fatal error: OOUI\Exception: OOUI\Theme::singleton was called with no singleton theme set. in /var/www/cx-ofb/vendor/oojs/oojs-ui/php/Theme.php:31 Stack trace: #0 /var/www/cx-ofb/vendor/oojs/oojs-ui/php/Element.php(259): OOUI\Theme::singleton() #1 /var/www/cx-ofb/vendor/oojs/oojs-ui/php/Tag.php(510): OOUI\Element->toString() #2 /var/www/cx-ofb/extensions/VisualEditor/includes/Hooks.php(260): OOUI\Tag->__toString() #3 /var/www/cx-ofb/includes/HookContainer/HookContainer.php(159): MediaWiki\Extension\VisualEditor\Hooks->onTextSlotDiffRendererTablePrefix() #4 /var/www/cx-ofb/includes/HookContainer/HookRunner.php(1338): MediaWiki\HookContainer\HookContainer->run() #5 /var/www/cx-ofb/includes/diff/TextSlotDiffRenderer.php(278): MediaWiki\HookContainer\HookRunner->onTextSlotDiffRendererTablePrefix() #6 /var/www/cx-ofb/includes/diff/DifferenceEngine.php(1048): TextSlotDiffRenderer->getTablePrefix() #7 /var/www/cx-ofb/includes/diff/DifferenceEngine.php(1028): DifferenceEngine->showTablePrefixes() #8 /var/www/cx-ofb/includes/page/ in /var/www/cx-ofb/vendor/oojs/oojs-ui/php/Tag.php on line 512