Fatal error: OOUI\Exception: OOUI\Theme::singleton was called with no singleton theme set. in /var/www/html/vendor/oojs/oojs-ui/php/Theme.php:31 Stack trace: #0 /var/www/html/vendor/oojs/oojs-ui/php/Element.php(259): OOUI\Theme::singleton() #1 /var/www/html/vendor/oojs/oojs-ui/php/Tag.php(510): OOUI\Element->toString() #2 /var/www/html/extensions/VisualEditor/includes/Hooks.php(244): OOUI\Tag->__toString() #3 /var/www/html/includes/HookContainer/HookContainer.php(159): MediaWiki\Extension\VisualEditor\Hooks->onTextSlotDiffRendererTablePrefix(Object(TextSlotDiffRenderer), Object(RequestContext), Array) #4 /var/www/html/includes/HookContainer/HookRunner.php(1335): MediaWiki\HookContainer\HookContainer->run('TextSlotDiffRen...', Array) #5 /var/www/html/includes/diff/TextSlotDiffRenderer.php(276): MediaWiki\HookContainer\HookRunner->onTextSlotDiffRendererTablePrefix(Object(TextSlotDiffRenderer), Object(RequestContext), Array) #6 /var/www/html/includes/diff/DifferenceEngine.php(1040): TextSlotDiffRenderer->getTablePrefix(Object(RequestContext), Object(MediaWiki\Title\Title)) #7 /var/www/html/includes/diff/DifferenceEngine.php(1026): DifferenceEngine->showTablePrefixes() #8 /var/www/html/includes/page/Article.php(1001): DifferenceEngine->showDiffPage(false) #9 /var/www/html/includes/page/Article.php(500): Article->showDiffPage() #10 /var/www/html/includes/page/ImagePage.php(153): Article->view() #11 /var/www/html/includes/actions/ViewAction.php(78): ImagePage->view() #12 /var/www/html/includes/actions/ActionEntryPoint.php(735): ViewAction->show() #13 /var/www/html/includes/actions/ActionEntryPoint.php(512): MediaWiki\Actions\ActionEntryPoint->performAction(Object(ImagePage), Object(MediaWiki\Title\Title)) #14 /var/www/html/includes/actions/ActionEntryPoint.php(153): MediaWiki\Actions\ActionEntryPoint->performRequest() #15 /var/www/html/includes/MediaWikiEntryPoint.php(185): MediaWiki\Actions\ActionEntryPoint->execute() #16 /var/www/html/index.php(55): MediaWiki\MediaWikiEntryPoint->run() #17 {main} in /var/www/html/vendor/oojs/oojs-ui/php/Tag.php on line 512