Fix issues reported by PHPStan

[javiereguiluz]

When we introduced PHPStan, we added lots of errors to a "baseline file" to ignore them instead of fixing them. So, let's fix them.

In my opinion there are two kinds of issues:

(1) Issues that are PHP errors or improvements. Such as https://github.com/symfony/demo/pull/1331/files We need to fix those.

(2) Issues that are solved by adding metadata for PHPStan. I'm not sure 100% about fixing these. This is a Symfony Demo app, so only Symfony is important. If these issues require lots of changes and future maintenance, I wouldn't fix them.

What do you think?

[javiereguiluz]

About (2) @stof added the following in #1332 (comment)

---

Well, it also helps IDEs that support generic classes (PHPStorm has partial support for them, improving it in each release).
Generics are actually a de-facto standard, being supported with the same syntax by phpstan, psalm, PHPStorm (and maybe VSCode but I haven't checked)

And MakerBundle generates that @extends tag now. So users generating a User entity today will have it.

[tacman]

What do you think of bumping to Symfony 6.1 (which would obviously require PHP 8.1)? If we're going to fix PHPStan errors to have an app that shows best practices, it seems like it'd be nice to leverage PHP 8.1 and Symfony 6.1.

Since demo 2.0 is for Symfony 6.0, we could make demo 2.1 for Symfony 6.1.

[stof]

@tacman upgrading to Symfony 6.1 is an unrelated topic (and in progress in #1339)

[kniziol]

No errors found. PHPStan said [OK] No errors. Details below:

$ ./vendor/bin/phpstan --memory-limit=-1 -vvv
Note: Using configuration file phpstan.neon.dist.
 44/44 [▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓] 100% < 1 sec/< 1 sec 40.0 MiB

Result cache is saved.

                                                                                                                        
 [OK] No errors                                                                                                         
                                                                                                                        

Used memory: 40 MB

$ php -v
PHP 8.1.12 (cli) (built: Oct 28 2022 18:58:22) (NTS)
Copyright (c) The PHP Group
Zend Engine v4.1.12, Copyright (c) Zend Technologies
    with Zend OPcache v8.1.12, Copyright (c), by Zend Technologies
    with Xdebug v3.2.0RC1, Copyright (c) 2002-2022, by Derick Rethans

[stof]

@kniziol running phpstan ignores the errors that are in the baseline (that's the goal of the baseline). To empty the baseline, you need to look at the baseline file (or to empty that file before running phpstan)