Some images converted to webp format has response type "octet-stream" and are empty in browser

Some images converted to webp format has response type "octet-stream" and are empty in browser.

If copy link of image and put it into new tab everything is good.

The problem was resolved by removing raw:
`header('Content-Length:'.$this->cache->fileSize($path));`

In the 
`public function outputImage($path, array $params)` file Server.php