Fatal error: OOUI\Exception: OOUI\Theme::singleton was called with no singleton theme set. in E:\xampp\htdocs\w\vendor\oojs\oojs-ui\php\Theme.php:31
Stack trace:
#0 E:\xampp\htdocs\w\vendor\oojs\oojs-ui\php\Element.php(259): OOUI\Theme::singleton()
#1 E:\xampp\htdocs\w\vendor\oojs\oojs-ui\php\Tag.php(507): OOUI\Element->toString()
#2 E:\xampp\htdocs\w\extensions\VisualEditor\includes\Hooks.php(244): OOUI\Tag->__toString()
#3 E:\xampp\htdocs\w\includes\HookContainer\HookContainer.php(161): MediaWiki\Extension\VisualEditor\Hooks->onTextSlotDiffRendererTablePrefix(Object(TextSlotDiffRenderer), Object(RequestContext), Array)
#4 E:\xampp\htdocs\w\includes\HookContainer\HookRunner.php(1334): MediaWiki\HookContainer\HookContainer->run('TextSlotDiffRen...', Array)
#5 E:\xampp\htdocs\w\includes\diff\TextSlotDiffRenderer.php(273): MediaWiki\HookContainer\HookRunner->onTextSlotDiffRendererTablePrefix(Object(TextSlotDiffRenderer), Object(RequestContext), Array)
#6 E:\xampp\htdocs\w\includes\diff\DifferenceEngine.php(942): TextSlotDiffRenderer->getTablePrefix(Object(RequestContext), Object(MediaWiki\Title\Title))
#7 E:\xampp\htdocs\w\includes\diff\DifferenceEngine.php(928): DifferenceEngine->showTablePrefixes()
#8 E:\xampp\htdocs\w\includes\page\Article.php(979): DifferenceEngine->showDiffPage(false)
#9 E:\xampp\htdocs\w\includes\page\Article.php(490): Article->showDiffPage()
#10 E:\xampp\htdocs\w\includes\actions\ViewAction.php(78): Article->view()
#11 E:\xampp\htdocs\w\includes\MediaWiki.php(583): ViewAction->show()
#12 E:\xampp\htdocs\w\includes\MediaWiki.php(363): MediaWiki->performAction(Object(Article), Object(MediaWiki\Title\Title))
#13 E:\xampp\htdocs\w\includes\MediaWiki.php(960): MediaWiki->performRequest()
#14 E:\xampp\htdocs\w\includes\MediaWiki.php(613): MediaWiki->main()
#15 E:\xampp\htdocs\w\index.php(50): MediaWiki->run()
#16 E:\xampp\htdocs\w\index.php(46): wfIndexMain()
#17 {main} in E:\xampp\htdocs\w\vendor\oojs\oojs-ui\php\Tag.php on line 509