Codeigniter 4 Error on XAMPP

Hi,

I am testing Codeigniter 4 on my windows 7 PC. I have downloaded the codeigniter 4 from github and copied all the files to my htdocs folder of my XAMPP installation on Windows 7. 

But I am getting an error

Quote:Fatal error: Default value for parameters with a class type hint can only be NULL in C:\xampp\htdocs\CodeIgniter4-develop\system\Config\DotEnv.php on line 121

Is there something I am missing?