[BUGFIX] Add fallback for link details

A link to a folder created in RTE leads to undefined
array key warning in frontend.

This has been fixed by using null coalescing
operator instead of ternary operator.

Resolves: #95519
Releases: master
Change-Id: I2f5315db87281825fc53a63fdf6edabc5a8a7b01
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/71496


Tested-by: core-ci <typo3@b13.com>
Tested-by: Nikita Hovratov <nikita.h@live.de>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Nikita Hovratov <nikita.h@live.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>

typo3/sysext/frontend/Classes/Typolink/FileOrFolderLinkBuilder.php

@@ -31,7 +31,7 @@ class FileOrFolderLinkBuilder extends AbstractTypolinkBuilder
      */
     public function build(array &$linkDetails, string $linkText, string $target, array $conf): LinkResultInterface
     {
-        $fileOrFolderObject = $linkDetails['file'] ?: $linkDetails['folder'];
+        $fileOrFolderObject = $linkDetails['file'] ?? $linkDetails['folder'] ?? null;
         // check if the file exists or if a / is contained (same check as in detectLinkType)
         if (!($fileOrFolderObject instanceof FileInterface) && !($fileOrFolderObject instanceof Folder)) {
             throw new UnableToLinkException(