[BUGFIX] Set correct return type for CommandRegistry::getCommandByIde…

…ntifier

The method `getCommandByIdentifier` can return `null`, therefore the
return type must be adjusted.

Resolves: #92313
Releases: 10.4, 9.5
Change-Id: I15b272ae922fb86012fe6412b767e5d83436a6ae
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/65757
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>

typo3/sysext/core/Classes/Console/CommandRegistry.php

@@ -158,9 +158,9 @@ public function getLegacyCommands(): \Generator
      * @param string $identifier
      * @throws CommandNameAlreadyInUseException
      * @throws UnknownCommandException
-     * @return Command
+     * @return Command|null
      */
-    public function getCommandByIdentifier(string $identifier): Command
+    public function getCommandByIdentifier(string $identifier): ?Command
     {
         $this->populateCommandsFromPackages();