From https://www.tigerton.se/wordpress/debug-felsoka-wordpress/

wordpress-enable-debug.php

											
//WP-CONFIG.PHP
// Turns WordPress debugging on
define('WP_DEBUG', true);

// Tells WordPress to log everything to the /wp-content/debug.log file
define('WP_DEBUG_LOG', true);

// Doesn't force the PHP 'display_errors' variable to be on
define('WP_DEBUG_DISPLAY', false);

// Hides errors from being displayed on-screen
@ini_set('display_errors', 0);

//FUNCTIONS.PHP
if (!function_exists('write_log')) {
  function write_log ( $log )  {
        if ( true === WP_DEBUG ) {
            if ( is_array( $log ) || is_object( $log ) ) {
                error_log( print_r( $log, true ) );
            } else {
                error_log( $log );
            }
        }
    }
}