[BUGFIX] Avoid undefined array key XmlSitemapRenderer

Avoid undefined array key warning in case 'config' is
not given in TypoScript settings.

Resolves: #98145
Releases: main, 11.5
Change-Id: I20df94bd34f9f7197eee7905f5aa1c2af35d0601
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/75529


Tested-by: core-ci <typo3@b13.com>
Tested-by: Oliver Hader <oliver.hader@typo3.org>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>

typo3/sysext/seo/Classes/XmlSitemap/XmlSitemapRenderer.php

@@ -87,7 +87,7 @@ class XmlSitemapRenderer
                     $config['provider'],
                     $request,
                     $sitemap,
-                    (array)$config['config']
+                    (array)($config['config'] ?? [])
                 );
 
                 $pages = $provider->getNumberOfPages();
@@ -118,7 +118,7 @@ class XmlSitemapRenderer
                     $sitemapConfig['provider'],
                     $request,
                     $sitemap,
-                    (array)$sitemapConfig['config']
+                    (array)($sitemapConfig['config'] ?? [])
                 );
 
                 $items = $provider->getItems();