Fatal error on setting CI_ENVIRONMENT to testing

I just downloaded the latest CI in my local xampp server. I was using php 8.2. When I changed the variable  CI_ENVIRONMENT = testing in  .env file. I got the below error:
Fatal error: Uncaught Error: Undefined constant "CodeIgniter\Config\SUPPORTPATH" in C:\xampp82\htdocs\imflancer\system\Config\AutoloadConfig.php:144 Stack trace: #0 C:\xampp82\htdocs\imflancer\system\Boot.php(244): CodeIgniter\Config\AutoloadConfig->__construct() #1 C:\xampp82\htdocs\imflancer\system\Boot.php(54): CodeIgniter\Boot::loadAutoloader() #2 C:\xampp82\htdocs\imflancer\public\index.php(56): CodeIgniter\Boot::bootWeb(Object(Config\Paths)) #3 {main} thrown in C:\xampp82\htdocs\imflancer\system\Config\AutoloadConfig.php on line 144

Requesting to check and fix the issue.

As I know, testing is not for developing your files. It's more for the framework.

Simple CI 4 project for beginners codeigniter-expenses ( topic )

As I know, testing is not for developing your files. It's more for the framework.

I think all the errors should be handled. Thank you for your respond.

See https://codeigniter.com/user_guide/gener...vironments

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