Fatal error: Cannot use System\Helper\StringHelper as String because 'String' is a special class name in /var/www/coastobs/System/Output/Formatter/Pdf.php on line 9

Fatal error: Uncaught Exception: Service 'System\Output\Formatter\Pdf' wasn't found in the dependency injection container. Potential reason can be: Invalid class or service name: System\Output\Formatter\Pdf in /var/www/coastobs/System/Core/ServiceLocator/Service.php:159 Stack trace: #0 /var/www/coastobs/System/Core/ServiceContainer.php(74): System\Core\ServiceLocator\Service::get('System\\Output\\F...', Array) #1 [internal function]: System\Core\ServiceContainer->System\Core\{closure}(Object(System\Model\ViewModel)) #2 /var/www/coastobs/System/Core/ServiceContainer.php(95): call_user_func(Object(Closure), Object(System\Model\ViewModel)) #3 /var/www/coastobs/System/Output/OutputFormatterContainer.php(55): System\Core\ServiceContainer->resolve(Object(Closure), Object(System\Model\ViewModel)) #4 /var/www/coastobs/System/Core/RequestProcess.php(102): System\Output\OutputFormatterContainer->getFormatter(Object(System\Model\ViewModel)) #5 /var/www/coastobs/System/Core/ErrorHandler.php(106): System\Core\RequestProcess->createRes in /var/www/coastobs/System/Core/ServiceLocator/Service.php on line 159