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(507): OOUI\Element->toString() #2 /var/www/html/extensions/VisualEditor/includes/Hooks.php(244): OOUI\Tag->__toString() #3 /var/www/html/includes/HookContainer/HookContainer.php(161): MediaWiki\Extension\VisualEditor\Hooks->onTextSlotDiffRendererTablePrefix(Object(TextSlotDiffRenderer), Object(DerivativeContext), Array) #4 /var/www/html/includes/HookContainer/HookRunner.php(1334): MediaWiki\HookContainer\HookContainer->run('TextSlotDiffRen...', Array) #5 /var/www/html/includes/diff/TextSlotDiffRenderer.php(273): MediaWiki\HookContainer\HookRunner->onTextSlotDiffRendererTablePrefix(Object(TextSlotDiffRenderer), Object(DerivativeContext), Array) #6 /var/www/html/includes/diff/DifferenceEngine.php(942): TextSlotDiffRenderer->getTablePrefix(Object(DerivativeContext), Object(MediaWiki\Title\Title)) #7 /var/www/html/includes/diff/DifferenceEngine.php(928): DifferenceEngine->showTablePrefixes() #8 /var/www/html/extensions/MobileFrontend/includes/specials/SpecialMobileDiff.php(189): DifferenceEngine->showDiffPage(true) #9 /var/www/html/extensions/MobileFrontend/includes/specials/SpecialMobileDiff.php(143): SpecialMobileDiff->displayDiffPage() #10 /var/www/html/extensions/MobileFrontend/includes/specials/MobileSpecialPage.php(71): SpecialMobileDiff->executeWhenAvailable('14') #11 /var/www/html/includes/specialpage/SpecialPage.php(727): MobileSpecialPage->execute('14') #12 /var/www/html/includes/specialpage/SpecialPageFactory.php(1621): MediaWiki\SpecialPage\SpecialPage->run('14') #13 /var/www/html/includes/MediaWiki.php(357): MediaWiki\SpecialPage\SpecialPageFactory->executePath('MobileDiff/14', Object(RequestContext)) #14 /var/www/html/includes/MediaWiki.php(960): MediaWiki->performRequest() #15 /var/www/html/includes/MediaWiki.php(613): MediaWiki->main() #16 /var/www/html/index.php(50): MediaWiki->run() #17 /var/www/html/index.php(46): wfIndexMain() #18 {main} in /var/www/html/vendor/oojs/oojs-ui/php/Tag.php on line 509