TYPO3 Core

The Following Code in TYPO3\CMS\Linkvalidator\Linktype\FileLinktype does not handle the possible return value of $resourceFactory->retrieveFileOrFolderObject which returns null in certain cases.
It also seems like the documentation of retrieveFileOrFolderObject does not hint the possibility that a null value can be returned.

    public function checkLink($url, $softRefEntry, $reference)
    {
        $resourceFactory = GeneralUtility::makeInstance(ResourceFactory::class);
        try {
            $file = $resourceFactory->retrieveFileOrFolderObject($url);
        } catch (FileDoesNotExistException $e) {
            return false;
        } catch (FolderDoesNotExistException $e) {
            return false;
        }
        return !$file->isMissing();
    }

I would propose something like this:

    public function checkLink($url, $softRefEntry, $reference)
    {
        $resourceFactory = GeneralUtility::makeInstance(ResourceFactory::class);
        try {
            $file = $resourceFactory->retrieveFileOrFolderObject($url);
        } catch (FileDoesNotExistException $e) {
            return false;
        } catch (FolderDoesNotExistException $e) {
            return false;
        }

        if (!is_null($file) {
            return !$file->isMissing();
        } else {
            return false;
        }
    }