function recursiveAsyncReadLine(){

    rl.question(name : , function(answer) {

        if(answer===exit){

            rl.close();

        }

        var kitty = new Kitten({name : answer});

        kitty.save(function(err, kitty){

            if(err){

                throw err;

            }

            kitty.speak();

            Kitten.find(function(err, kittens){

                if(err){

                    throw err;

                }

                console.log(kittens);

                recursiveAsyncReadLine();

            });

        });

    });

}

I tried to change the code above with promise.

function recursiveAsyncReadLine(){

    rl.question(name: )

    .then((answer)=>{

        if(answer===exit){

            rl.close();

        }

        var kitty = new Kitten({name : answer});

        return kitty.save();

    })

    .then((kitty)=>{

        kitty.speak();

        return Kitten.find();

    })

    .then((kittens)=>{

        console.log(kittens);

        recursiveAsyncReadLine();           

    })

    .catch((err)=>{

        throw err;

    });

}

But it doesn't work with a message

TypeError: Cannot read property 'then' of undefined

The error occured at the first 'then' statement.

I'm not certain that I understood Promise correctly. Where did I make a mistake?