ISAICP-9121: Logo can be null.

web/modules/custom/joinup_group/src/Form/AnnouncementForm.php

@@ -319,7 +319,7 @@ protected function getArguments(): array {
         'value' => $group->toUrl('member-overview')->setAbsolute()->toString(),
       ],
       '@group_logo' => [
-        'value' => $group->getLogoAsUrl()->setAbsolute()->toString(),
+        'value' => $group->getLogoAsUrl()?->setAbsolute()->toString(),
       ],
       '@author_name' => [
         'value' => $sender->getDisplayName(),