OCP class throws private exception

[nickvergessen]

Talk was catching it for a while but with the Psalm5 update it started complaining:

ERROR: UndefinedClass - lib/TInitialState.php:143:13 - Class, interface or enum named OC\User\NoUserException does not exist (see https://psalm.dev/019)
			} catch (NoUserException $e) {

server/lib/public/Files/IRootFolder.php

Line 28 in 44a8ebd

use OC\User\NoUserException;

server/lib/public/Files/IRootFolder.php

Line 42 in 44a8ebd

* @throws NoUserException

Also extending the non public Emitter is not too good, but I'm totally fine providing a stub for that. But the OC catch I don't want to "mock".

I guess we need to make a new class, but if that extends the private one Psalm will complain again...

[joshtrichards]

Related: #33239