check "never" return type more strictly

[kkmuffme]

• require explicit "never" return type when function always exits
• error if function does not exit, but return type explicitly contains "never"
• Fix: Missing InvalidReturnType check when exit; #8175
• Fix: InvalidReturnType due to void and null not treated the same #8178

[orklah]

This snippet should still be working:
https://psalm.dev/r/3ec4cb4877

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/3ec4cb4877

<?php

abstract class Car{
 	abstract public function getFuel(): string{}   
}

class ThermalCar{
 	public function getFuel(): string { return 'Gas';}
}

class ElectricCar{
 	public function getFuel(): never { throw new DomainException('EV need no fuel'); }
}

Psalm output (using commit 7c83878):

No issues!

[kkmuffme]

The failing test is unrelated to the changes of this PR.

As discussed it won't give an error for #8175 (comment) / #8624

Ready for review

[kkmuffme]

@orklah if I resolve the conflicts which popped up in the meantime, could this get reviewed & merged now?

[orklah]

Yeah probably, did you check the snippet I posted above?

[kkmuffme]

Afair yes, this is still working without errors. (I even added a test for a similar case)

[orklah]

Thanks!