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