These 500-internal-server-error messages are tough to troubleshoot, because they can be caused by all kinds of things.
The errorlog info you shared doesn't seem to be relevant to attempts to open your /shop/ files. Sometimes the errorlog isn't updated right away as caching prevents you from being able to get all the latest entries. Perhaps grabbing the errorlog again may help find more information about attempts to access the /shop/index.php area.
You could also try temporarily renaming the /includes/.htaccess file to htaccess_bak to see if there's a directive in there that's conflicting with your server's configuration.
(Not a big fan of doteasy hosting)



