[TASK] Avoid implicitly nullable class method parameter

With PHP 8.4 marking method parameter implicitly nullable
is depreacted and will emit a `E_DEPRECATED` warning. One
recommended way to resolve this, is making it explicitly
nullable using the `?` nullable operator. [1]

In cases, where are implicitly nullable parameter exists
before not-nullable parameters in a method or constructor,
making it explicitly nullable will emit a

  Optional parameter <paramname> declared before required
  parameter <paramname> is implicitly treated as a required
  parameter

since PHP 8.0 [2].

This change adds the `?` nullable operator and removes the
null default value for the first parameter, which mitigates
both issues.

This prepares the way towards PHP 8.4 compatibility.

[1] https://php.watch/versions/8.4/implicitly-marking-parameter-type-nullable-deprecated
[2] https://php.watch/versions/8.0/deprecate-required-param-after-optional

Resolves: #103927
Releases: main, 12.4, 11.5
Change-Id: I0ba574769e5b95852379aa30f03d45715aec2055
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/84363


Tested-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: core-ci <typo3@b13.com>

typo3/sysext/scheduler/Classes/Task/FileStorageIndexingAdditionalFieldProvider.php

@@ -50,11 +50,16 @@ class FileStorageIndexingAdditionalFieldProvider implements AdditionalFieldProvi
     /**
      * Add a select field of available storages.
      *
-     * @param FileStorageIndexingTask $task When editing, reference to the current task object. NULL when adding.
-     * @param array $taskInfo
-     * @return array Array containing all the information pertaining to the additional fields
+     * @param FileStorageIndexingTask|null $task When editing, reference to the current task object. NULL when adding.
+     * @param array $taskInfo Reference to the array containing the info used in the add/edit form
+     * @return array{
+     *     code: string,
+     *     label: string,
+     *     cshKey: string,
+     *     cshLabel: string,
+     * }
      */
-    protected function getAllStoragesField(FileStorageIndexingTask $task = null, $taskInfo)
+    protected function getAllStoragesField(?FileStorageIndexingTask $task, array $taskInfo): array
     {
         /** @var ResourceStorage[] $storages */
         $storages = GeneralUtility::makeInstance(StorageRepository::class)->findAll();