[TASK] Fix undefined array key error in ActionMenuItemViewHelper

The variable $this->arguments['selected'] is not always set.

Resolves: #95283
Releases: master
Change-Id: I24ac026300c04bd9bf2e5f2bab580cdf847df5ad
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/71169
Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Oliver Bartsch <bo@cedev.de>

typo3/sysext/fluid/Classes/ViewHelpers/Be/Menus/ActionMenuItemViewHelper.php

@@ -113,7 +113,7 @@ protected function evaluateSelectItemState(string $controller, string $action, a
             array_merge(['controller' => $controller, 'action' => $action], $arguments)
         );
         if (
-            $this->arguments['selected'] ||
+            ($this->arguments['selected'] ?? false) ||
             array_diff($flatRequestArguments, $flatViewHelperArguments) === []
         ) {
             $this->tag->addAttribute('selected', 'selected');