Fix: typescript annotation for server

[sviande]

PR Checklist

• [ X] I have run npm test locally and all tests are passing.
• [ X] I have added/updated tests for any new behavior.
• [ X] If this is a significant change, an issue has already been created where the problem / solution was discussed: [N/A, or add link to issue here]

PR Description

Fix typescript annotation accordingly to the current behavior

[nulltoken]

@sviande Can you please elaborate on that proposed change? What doesn't work for you with the current signature?