the idea is never to give out file names, line numbers, and cryptic codes to the user. Use trigger_error() after you used set_error_handler() to register your own callback function which either logs or emails the error codes to you, and echo a simple friendly message to the user.
And turn on a more verbose error handler function when you need to debug your scripts. In my init.php scripts I always have:
if (_DEBUG_) {
set_error_handler ('debug_error_handler');
}
else {
set_error_handler ('nice_error_handler');
}