[BUGFIX] OtherLanguageContent: show fallback language icon

Since the default language can be different from site
configuration to site configuration, "flags-multiple" icon
is used instead of the fallback "default-not-found" icon
when no default language is configured (e.g. when editing
a translated sys_file_metadata record in filelist module).

Resolves: #88909
Releases: master
Change-Id: Ie755cc06b43e4b735000ab598f14853773d58ced
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/61432


Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Susanne Moog <look@susi.dev>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Susanne Moog <look@susi.dev>

typo3/sysext/backend/Classes/Form/FieldWizard/OtherLanguageContent.php

@@ -68,8 +68,9 @@ class OtherLanguageContent extends AbstractNode
             $defaultLanguageRow['pid']
         );
         if ($defaultLanguageValue !== '') {
+            $iconIdentifier = $this->data['systemLanguageRows'][0]['flagIconIdentifier'] ?: 'flags-multiple';
             $html[] = '<div class="t3-form-original-language">';
-            $html[] =   $iconFactory->getIcon($this->data['systemLanguageRows'][0]['flagIconIdentifier'], Icon::SIZE_SMALL)->render();
+            $html[] =   $iconFactory->getIcon($iconIdentifier, Icon::SIZE_SMALL)->render();
             $html[] =   $this->previewFieldValue($defaultLanguageValue);
             $html[] = '</div>';
         }