How to supress errors in config.php except for a specific ip

[bzcomputers]

I'd like to do some troubleshooting on a live 4.2.2 site. It currently has this in the config.php:

define('SKIP_ALL_ERRORS', true);

I'd like to bypass this for my specific id address so I can track down errors/warnings. I've tried something like this below:

if ($_SERVER['REMOTE_ADDR'] != 'xxx.xxx.xx.xx') { define('SKIP_ALL_ERRORS', true); }

...but it gives errors, I know I'm missing something obvious.