E_WARNING: Undefined variable $http_response_header is reported when file_get_contents fails to fetch the specified $url. This seems to happen because HTTP Wrapper doesn't set $http_response_header when it fails.
Since PHP 8 accesses to undefined variables are reported as E_WARNING, this became more visible and noisier.
This PR avoids the warning by using a coalescing operator.
E_WARNING: Undefined variable $http_response_headeris reported whenfile_get_contentsfails to fetch the specified$url. This seems to happen because HTTP Wrapper doesn't set$http_response_headerwhen it fails.Since PHP 8 accesses to undefined variables are reported as E_WARNING, this became more visible and noisier.
This PR avoids the warning by using a coalescing operator.