postgresql – select returns null rows, although some entries should be returned

I have a Postgres database that is a simple demo forum. There are two tables that are called

theme

id | topic_id (the parent topic) | name | description
-------------------------------------------------- -----
uuid | uuid | Text | text

and thread

id | topic_id | name | made in
-------------------------------------------------- -----
uuid | uuid | Text | Timestamp without time zone

By using an Express REST API, I want to get all the information about a topic. I enter his ID and would like to receive a result

{
parentTopic: {}, // could be null if no parent is available
Surname: "",
Description: "",
child topics: [{}, {}, {}],
threads: [{}, {}, {}] // should be sorted by create_at
}

As far as I know, it is not possible to return such a result. However, I tried to create a query to get this information. Maybe I can assign them later with some code.

CHOOSE
currentTopic.name,
currentTopic.description,
parentTopic.id AS parentTopicId,
parentTopic.name AS parentTopicName,
parentTopic.description AS parentTopicDescription,
childTopic.id AS childTopicId,
childTopic.name AS childTopicName,
childTopic.description AS childTopicDescription,
linkedThread.id AS threadId,
linkedThread.name AS ThreadName,
linkedThread.created_at AS threadCreatedAt
FROM
topic currentTopic
INNER JOIN
topic parentTopic ON currentTopic.topic_id = parentTopic.id
INNER JOIN
topic childTopic ON currentTopic.id = childTopic.topic_id
INNER JOIN
thread linkedThread ON currentTopic.id = linkedThread.topic_id
FROM WHERE
currentTopic.id = & # 39; 624aaab6-2d2d-45dc-a425-c2863f05779c & # 39;
SORT BY
linkedThread.created_at;

During execution (I am using pgAdmin), no error occurs, but 0 rows are returned. I made sure that some entries should be retrieved.

Is something wrong with this question? Is there a way to improve the query to get a ready-to-use result (the JS object mentioned above)?