Fatal error Issue

[Sumayah90]

Hi

I have faced this issue after I install the extension
I am using Magento 2.1 PHP 7.0
Ubuntu server

Fatal error: Declaration of Staempfli\Pdf\Model\View\PdfResult::render(Magento\Framework\App\Response\HttpInterface $response) must be compatible with Magento\Framework\Controller\AbstractResult::render(Magento\Framework\App\ResponseInterface $response) in /srv/users/sumayah/apps/magento/public/magento2/vendor/staempfli/magento2-module-pdf/Model/View/PdfResult.php on line 16

How can I fix the issue?

thanks