I got it working by moving the "Whoops Run" in my index.php file, right after defining my development environment and error reporting settings (around line 70 in the CI index.php file) :
/*
*---------------------------------------------------------------
* ERROR REPORTING
*---------------------------------------------------------------
*
* Different environments will require different levels of error reporting.
* By default development will show errors but testing and live will hide them.
* 2017-08-21: Adding Whoops profiler
*/
use Whoops\Handler\PrettyPageHandler;
switch (ENVIRONMENT)
{
case 'development':
case 'staging':
error_reporting(-1);
ini_set('display_errors', 1);
error_reporting(E_ALL ^ E_WARNING ^ E_USER_WARNING ^ E_NOTICE ^ E_DEPRECATED );
$whoops = new \Whoops\Run;
$whoops->pushHandler(new Whoops\Handler\PrettyPageHandler());
$whoops->register();
break;
case 'testing':
case 'production':
ini_set('display_errors', 0);
if (version_compare(PHP_VERSION, '5.3', '>='))
{
error_reporting(E_ALL & ~E_NOTICE & ~E_DEPRECATED & ~E_STRICT & ~E_USER_NOTICE & ~E_USER_DEPRECATED);
}
else
{
error_reporting(E_ALL & ~E_NOTICE & ~E_STRICT & ~E_USER_NOTICE);
}
break;
default:
header('HTTP/1.1 503 Service Unavailable.', TRUE, 503);
echo 'The application environment is not set correctly.';
exit(1); // EXIT_ERROR
}
A comment in this Github Whoops issue tipped me off!