I try to get a doc from firestore and send to the client the result by the object. But the result value is null. How can I get a proper return object?

 // sending results from the server
      db.collection("devices")
        .doc(data.id)
        .get()
        .then((res) => {
          console.log(res.data().online);
          if(res.exists()){
            return {          
              'success': true, 
              'online': res.data().online
            };
          }
          else{
            return {          
              'success': false, 
              'message': 'Could not find doc.'
            };
          }     
        })
   
    // received data
      const getOnlineState = async (device) => {
        const response = await readState(device)
          console.log(response);
      };

// console 
{data: null}data: null[[Prototype]]: Object

 

I want to see the return object.