Fatal error: OOUI\Exception: OOUI\Theme::singleton was called with no singleton theme set. in /home/df21admin/df-21.net/wiki/vendor/oojs/oojs-ui/php/Theme.php:31 Stack trace: #0 /home/df21admin/df-21.net/wiki/vendor/oojs/oojs-ui/php/Element.php(259): OOUI\Theme::singleton() #1 /home/df21admin/df-21.net/wiki/vendor/oojs/oojs-ui/php/Tag.php(507): OOUI\Element->toString() #2 /home/df21admin/df-21.net/wiki/extensions/VisualEditor/includes/Hooks.php(244): OOUI\Tag->__toString() #3 /home/df21admin/df-21.net/wiki/includes/HookContainer/HookContainer.php(161): MediaWiki\Extension\VisualEditor\Hooks->onTextSlotDiffRendererTablePrefix(Object(TextSlotDiffRenderer), Object(RequestContext), Array) #4 /home/df21admin/df-21.net/wiki/includes/HookContainer/HookRunner.php(1332): MediaWiki\HookContainer\HookContainer->run('TextSlotDiffRen...', Array) #5 /home/df21admin/df-21.net/wiki/includes/diff/TextSlotDiffRenderer.php(273): MediaWiki\HookContainer\HookRunner->onTextSlotDiffRendererTablePrefix(Object(TextSlotDiffRenderer), Object(RequestContext), Array) #6 /home/df21admin/df-21.net/wiki/includes/diff/DifferenceEngine.php(942): TextSlotDiffRenderer->getTablePrefix(Object(RequestContext), Object(MediaWiki\Title\Title)) #7 /home/df21admin/df-21.net/wiki/includes/diff/DifferenceEngine.php(928): DifferenceEngine->showTablePrefixes() #8 /home/df21admin/df-21.net/wiki/includes/page/Article.php(979): DifferenceEngine->showDiffPage(false) #9 /home/df21admin/df-21.net/wiki/includes/page/Article.php(490): Article->showDiffPage() #10 /home/df21admin/df-21.net/wiki/includes/page/CategoryPage.php(63): Article->view() #11 /home/df21admin/df-21.net/wiki/includes/actions/ViewAction.php(78): CategoryPage->view() #12 /home/df21admin/df-21.net/wiki/includes/MediaWiki.php(583): ViewAction->show() #13 /home/df21admin/df-21.net/wiki/includes/MediaWiki.php(363): MediaWiki->performAction(Object(CategoryPage), Object(MediaWiki\Title\Title)) #14 /home/df21admin/df-21.net/wiki/includes/MediaWiki.php(960): MediaWiki->performRequest() #15 /home/df21admin/df-21.net/wiki/includes/MediaWiki.php(613): MediaWiki->main() #16 /home/df21admin/df-21.net/wiki/index.php(50): MediaWiki->run() #17 /home/df21admin/df-21.net/wiki/index.php(46): wfIndexMain() #18 {main} in /home/df21admin/df-21.net/wiki/vendor/oojs/oojs-ui/php/Tag.php on line 509