[BUGFIX] Handle invalid source string correctly in ImageService

The ImageService->getImageFromSourceString() tries
to retrieve a FileInterface from a given source string,
e.g. with the "EXT:" prefix. However, because the used
ResourceFactory->retrieveFileOrFolderObject() method
can also return a FolderInterface or NULL, this must be
handled to prevent a TypeError.

Therefore, the final $image value is now checked for being
a FileInterface. Otherwise NULL is returned, which is then
handled with a custom exception in the calling `getImage()`
method.

Resolves: #94495
Releases: master, 10.4
Change-Id: I95836fd3c1701cc8c9b9e07c5b8e10a7fb9ee9cc
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/69729
Tested-by: core-ci <typo3@b13.com>
Tested-by: Jochen <rothjochen@gmail.com>
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Geert Boetzkes <geert.boetzkes@beech.it>
Reviewed-by: Jochen <rothjochen@gmail.com>
Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Oliver Bartsch <bo@cedev.de>

Author: o-ba

typo3/sysext/extbase/Classes/Service/ImageService.php

@@ -136,6 +136,9 @@ public function getImage(string $src, $image, bool $treatIdAsReference): FileInt
             $image = $image->getOriginalResource();
         }
 
+        if ($image === null) {
+            throw new \UnexpectedValueException('Supplied file is NULL, but must be File or FileReference.', 1625585157);
+        }
         if (!($image instanceof File || $image instanceof FileReference)) {
             throw new \UnexpectedValueException('Supplied file object type ' . get_class($image) . ' for ' . $src . ' must be File or FileReference.', 1382687163);
         }
@@ -148,9 +151,9 @@ public function getImage(string $src, $image, bool $treatIdAsReference): FileInt
      *
      * @param string $src
      * @param bool $treatIdAsReference
-     * @return FileInterface|FileReference|\TYPO3\CMS\Core\Resource\Folder
+     * @return FileInterface|null
      */
-    protected function getImageFromSourceString(string $src, bool $treatIdAsReference): object
+    protected function getImageFromSourceString(string $src, bool $treatIdAsReference): ?FileInterface
     {
         if (($GLOBALS['TYPO3_REQUEST'] ?? null) instanceof ServerRequestInterface
             && ApplicationType::fromRequest($GLOBALS['TYPO3_REQUEST'])->isBackend()
@@ -173,7 +176,9 @@ protected function getImageFromSourceString(string $src, bool $treatIdAsReferenc
             // We have a combined identifier or legacy (storage 0) path
             $image = $this->resourceFactory->retrieveFileOrFolderObject($src);
         }
-        return $image;
+
+        // Check the resolved image as this could also be a FolderInterface
+        return $image instanceof FileInterface ? $image : null;
     }
 
     /**