Bug: exception message might display in production

[kenjis]

This is PoC to show the current PageNotFoundException handling is not good.

.env:

CI_ENVIRONMENT = production

--- a/app/Config/Events.php
+++ b/app/Config/Events.php
@@ -4,6 +4,7 @@ namespace Config;
 
 use CodeIgniter\Events\Events;
 use CodeIgniter\Exceptions\FrameworkException;
+use CodeIgniter\Exceptions\PageNotFoundException;
 
 /*
  * --------------------------------------------------------------------
@@ -46,3 +47,7 @@ Events::on('pre_system', static function () {
         Services::toolbar()->respond();
     }
 });
+
+Events::on('pre_system', static function () {
+    throw new PageNotFoundException('this is raw exception message.');
+});

Navigate to http://localhost:8080/ and you will see:

404 - File Not Found
this is raw exception message.