Changed:

- used `$this->getRequestValue($request, 'foo', <bar>)` instead of `$request['foo'] ?? <bar>`
- fixed wrong variable naming
- changed double-quotes to single
- see https://github.com/friendica/friendica/issues/11631#issuecomment-1196410497

src/Module/Api/Friendica/Notification/Seen.php

@@ -47,7 +47,7 @@ class Seen extends BaseApi
 			throw new BadRequestException('Invalid argument count');
 		}
 
-		$id = intval($request['id'] ?? 0);
+		$id = intval($this->getRequestValue($request, 'id', 0));
 
 		$include_entities = $this->getRequestValue($request, 'include_entities', false);