how to implement custom exception management in CodeIgniter 4?

While that functionality is something I'd like to see expanded on in the framework's future, there is no global custom exception handling. You might be able to attach your own handler during system boot by registering it with set_error_handler but that might cause conflicts with the one that we already register. I'm not 100% sure.

I see that you fixed your immediate error, though. And using try/catch blocks and not relying on a global handler is what I was going to recommend anyway.

I am interested in your opinion about this PR https://github.com/codeigniter4/CodeIgniter4/pull/5355