[BUGFIX] Avoid error in imageLinkWrap for non-existing files

ImageLinkWrap may not get a valid file object but will still try to
access methods on it which will fail. This patch implements a null check
resulting in simply not linking the image if the given file resource is
invalid.

Resolves: #88879
Releases: master, 9.5
Change-Id: I723596aa3b0a274a3565492b3d67a30b9d52389f
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/63914
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Guido Schmechel <guido.schmechel@brandung.de>
Reviewed-by: Daniel Goerz <daniel.goerz@posteo.de>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Frank Nägler <frank.naegler@typo3.org>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: Frank Nägler <frank.naegler@typo3.org>

typo3/sysext/frontend/Classes/ContentObject/ContentObjectRenderer.php

@@ -1314,7 +1314,7 @@ public function imageLinkWrap($string, $imageFile, $conf)
         }
 
         // Create imageFileLink if not created with typolink
-        if ($content === $string) {
+        if ($content === $string && $file !== null) {
             $parameterNames = ['width', 'height', 'effects', 'bodyTag', 'title', 'wrap', 'crop'];
             $parameters = [];
             $sample = isset($conf['sample.']) ? $this->stdWrap($conf['sample'], $conf['sample.']) : $conf['sample'];