How to show a error page when there is a php mistake?

[eluser]Jelmer[/eluser]
Check out UhOh from Dan Horrigan.

And just to get errors to show in CI without modification change the error_reporting at the top of the main index.php file:

Code:

error_reporting( E_ALL );
ini_set('display_errors', 'On');

Just don't forget to turn errors off and set error_reporting(0) once your site goes live.