Returning un-used date

Here you are telling the database to return everything after inserting them but why?
You are not using them in the controller at all !!

https://github.com/GSG-G10/W7-ToDo/blob/9732c79189a00e005547aec1357720691b619383/server/database/queries/add_user_query.js#L3

https://github.com/GSG-G10/W7-ToDo/blob/9732c79189a00e005547aec1357720691b619383/server/controllers/createUser.js#L7-L8

Start with server/database/queries/add_user_query.js at the linked line, then inspect server/controllers/createUser.js lines 7-8 to confirm whether the returned database value is consumed. Done means the query no longer returns unused data while user creation continues to work as before; check any available user-creation test or run the relevant application flow.

Written by the indexing model from the issue text.