Articles, Unified-index; Indexing errors when a Tiki article has a url source

• Regression

On a quite big and several time upgraded Tiki all unified-index errors were running without errors.
Since a few month I see an error for each article that has the field source filled with an URL.

2022-11-14T07:55:37+00:00 INFO (6): addDocument article 470 {"memoryUsage":"38.5 MiB"}
2022-11-14T07:55:37+00:00 ERR (3): NOTICE: Trying to access array offset on value of type bool {"code":null,"file":"/var/www/vhosts/xxxx/xxxx/lib/core/Search/ContentSource/ArticleSource.php","line":53}
2022-11-14T07:55:37+00:00 ERR (3): NOTICE: Trying to access array offset on value of type bool {"code":null,"file":"/var/www/vhosts/xxxx/xxxx/lib/core/Search/ContentSource/ArticleSource.php","line":56}

$rss_relations = TikiLib::lib('relation')->get_object_ids_with_relations_from('article', $objectId, 'tiki.rss.source');
        $sitetitle = '';
         $siteurl = '';
        if ($rss_relations) {
            $rssId = reset($rss_relations);
            $rssModule = TikiLib::lib('rss')->get_rss_module($rssId);
            if ($rssModule['sitetitle']) {
                 $sitetitle = $rssModule['sitetitle'];
            }
            if ($rssModule['siteurl']) {
                $siteurl = $rssModule['siteurl'];
            }
        }

This bug has been demonstrated on show2.tiki.org

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