When I invoke an action it returns undefined

Hi, in my project I have defined the following action handler that is used to pair two devices:

**Server servient.**
```
let allowedID = [1, 2];

thing.setActionHandler('pairing', (id) => {
return allowedID.includes(id)

});
```

Then in my client Servient I invoke the action in the following way and it returns undefined when it should be returning true or false:

**Client Servient.**
```
thing.invokeAction('pairing', 1).then(x => console.log(x));
```

I don't know if my code is wrong or if it is another error.

Thanks in advance