Wordpress has two functions related to SQL queries and their errors as mentioned in What Is The Difference Between suppress_errors() And hide_errors() in $wpdb?
From what I've read setting
wp-config.php will set
hide_errors() so that mySql errors aren't show - but if the site can't connect to the database you'll still error:
WordPress database error: [MySQL server has gone away]`
Without modifying the core file
wp-includes/wp-db.php and setting the line ~69 to
var $suppress_errors = true;
(which is what I've done for now), how can I set
suppress_errors to false without modifying the core?