bug #45675 [Runtime] Fix passing $debug parameter to ErrorHandler (Kocal)

This PR was merged into the 5.4 branch.

Discussion
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[Runtime] Fix passing $debug parameter to `ErrorHandler`

| Q             | A
| ------------- | ---
| Branch?       | 5.4
| Bug fix?      | yes
| New feature?  | no <!-- please update src/**/CHANGELOG.md files -->
| Deprecations? | yes/no <!-- please update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tickets       | Fix #... <!-- prefix each issue number with "Fix #", no need to create an issue if none exist, explain below instead -->
| License       | MIT
| Doc PR        | symfony/symfony-docs#... <!-- required for new features -->

As discussed with `@nicolas`-grekas on Slack, we think we should pass `$debug` parameter instead of `true`, since the 2nd argument of [`ErrorHandler`](https://github.com/symfony/symfony/blob/5.4/src/Symfony/Component/ErrorHandler/ErrorHandler.php#L184) is called `$debug`.

Commits
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a39f4f31e2 [Runtime] Fix passing $debug parameter to `ErrorHandler`

Author: nicolas-grekas

Internal/SymfonyErrorHandler.php

@@ -29,7 +29,7 @@ public static function register(bool $debug): void
         if (class_exists(ErrorHandler::class)) {
             DebugClassLoader::enable();
             restore_error_handler();
-            ErrorHandler::register(new ErrorHandler(new BufferingLogger(), true));
+            ErrorHandler::register(new ErrorHandler(new BufferingLogger(), $debug));
         }
     }
 }