[PHP 8.1] Exception codes should be numeric and not NULL

1. Should we add a deprecation warning that the exception code should be an integer and add a test for that.
2. Is this the only exception with this problem? Or do we need to do all by core added exceptions?

Using git grep -E 'throw new \w+Exception.*NULL' I found 2 more places

Re #3 I see no way to add deprecation message because all exceptions are inherited from \Exception which declared as public function __construct($message = "", $code = 0, Throwable $previous = null) {} I found few places where it defined as int $code = 0 and few places in SF ?int $code = 0 so probably only static analysis may help

@andypost: Thank you for the git grep command. Learned something new.

When I use the command git grep -E 'throw new \w+Exception.*NULL' after applying the patch, I get a number of results.
Most of them are fake positives, only 2 are not:
- core/modules/jsonapi/src/Revisions/ResourceVersionRouteEnhancer.php: throw new CacheableHttpException($cacheability, 501, $message, NULL, []);
- core/modules/jsonapi/src/Revisions/ResourceVersionRouteEnhancer.php: throw new CacheableHttpException($cacheability, 501, $message, NULL, []);
The last parameter is the one for the variable $code. Only when calling the parent exception the value of code is put into the variable $headers. The parent is vendor/symfony/http-kernel/Exception/HttpException.php. Not sure if we want to fix it in this issue.

All other changes are for me RTBC.

All changes look good to me.
I could not find any other instances with this problem.
For me it is RTBC.

@longwave: Thanks for the reply.

I think it still makes sense to fix broken arguments and decide about headers in related issue because @alexpott suggests to remove it in #3002352-29: CacheableHttpException must pass a $headers argument to HttpException

IMO the fix perfectly fits into scope of this issue

1. +++ b/core/lib/Drupal/Core/Http/Exception/CacheableHttpException.php
   @@ -18,7 +18,7 @@ class CacheableHttpException extends HttpException implements CacheableDependenc
   -    parent::__construct($statusCode, $message, $previous, $code);
   +    parent::__construct($statusCode, $message, $previous, [], $code);
   
   +++ b/core/modules/jsonapi/src/Revisions/ResourceVersionRouteEnhancer.php
   @@ -105,7 +105,7 @@ public function enhance(array $defaults, Request $request) {
   -        throw new CacheableHttpException($cacheability, 501, $message, NULL, []);
   

   I do not think we can do this change. It now works when you do: throw new CacheableHttpException($cacheability, 501, $message, NULL, []);. With this change it will be a BC break.

2. +++ b/core/modules/jsonapi/src/Revisions/ResourceVersionRouteEnhancer.php
   @@ -105,7 +105,7 @@ public function enhance(array $defaults, Request $request) {
   -        throw new CacheableHttpException($cacheability, 501, $message, NULL, []);
   +        throw new CacheableHttpException($cacheability, 501, $message, NULL, 0);
   
   @@ -151,7 +151,7 @@ public function enhance(array $defaults, Request $request) {
   -        throw new CacheableHttpException($cacheability, 501, $message, NULL, []);
   +        throw new CacheableHttpException($cacheability, 501, $message, NULL, 0);
   

   Could we change this to: throw new CacheableHttpException($cacheability, 501, $message, NULL); or maybe even to: throw new CacheableHttpException($cacheability, 501, $message);. We do not need to add the default parameter values.

The solution from #12 looks good to me. Can we also add a comment with why we have this solution.

Added workaround with todo but I'm sure as there's no usage in contrib and jsonapi is "fresh" it needs no reason

It looks good to me now.
Back to RTBC.

Committed 65fb382 and pushed to 9.3.x. Thanks!