So I am always trying to google for this code that goes into your wp-config.php file. However, I never find what I’m looking for and always have to sift through my wp-config files until I find it on one of the sites I manage.

You can use the following code in your wp-config.php file in order to turn on errors, but keep notices and deprecation notices off. If you have a lot of plugins, you will especially appriciate this as turning on the standard wordpress debuging can cause quite the ruckus.
[php]/**
* For developers: WordPress debugging mode.
*
* Change this to true to enable the display of notices during development.
* It is strongly recommended that plugin and theme developers use WP_DEBUG
* in their development environments.
*/
//define(‘WP_DEBUG’, true);
@ini_set(‘display_errors’,’On’);
@ini_set(‘log_errors’,’Off’);
//@ini_set(‘error_log’,’/home/example.com/logs/php_error.log’);
error_reporting(E_ALL ^ E_NOTICE ^ E_USER_NOTICE ^ E_DEPRECATED);[/php]