Steps to reproduce the issue

Install clean 5.0.2 with the French Canada language package set as default front-end language.

Expected result

Website displays in Canadian French.

Actual result

Error 500 on frontend, and some backend screens (ex., Global Configuration screen).

System information (as much as possible)

I'm running this loacally on Windows (XAMPP) PHP 8.1.4, MariaDB 10.4.24.

Additional comments

The error stack trace reveals:

Compile Error: Cannot declare class En_CALocalise, because the name is already in use

C:\xampp\htdocs\betaec\administrator\language\fr-CA\localise.php:23

Changing the abstract classname from En_CALocalise to Fr_CALocalise appears to resolve the issue.