FluidTYPO3\Vhs\ViewHelpers\Resource\LanguageViewHelper::getResolvedExtensionName PHP Method

    protected function getResolvedExtensionName()
    {
        $extensionName = $this->arguments['extensionName'];
        if (null === $extensionName && true === $this->controllerContext instanceof ControllerContext) {
            $request = $this->controllerContext->getRequest();
            $extensionName = $request->getControllerExtensionName();
        }
        if (true === empty($extensionName)) {
            throw new Exception('Cannot read extension name from ControllerContext and value not manually specified');
        }
        return $extensionName;
    }