Custom PHP Error Page for NGINX Not Responding To '?=_'

I've recently created a custom error page with configuration such as:

error_page 404 /error.php?code=404

But it seems to show up only error.php instead of error.php?code=404.

I've cheked the php file by accessing /error.php?code=404 in my browser and it works fine. I am using $Get

Please help. Thanks a lot.