Unhandled rejection rangerror: invalid status code: 0

I'm getting this problem and I can't get out of it. What I'm going to do it's to publish "a post" (json), save it into MongoDB.

exports.create_a_topic = function(req, res) {
return new Promise((resolve,reject) => {

var newTopic = new Topic({
    topic_type: req.body.topic_type,
    properties: req.body.properties[0]
});

newTopic.save()
.then(() => resolve({ status: 201, message: 'Topic published Successfully!' }))
    .catch((err) => {
        if (err.code == 11000) {
            reject({ status: 409, message: 'Topic Already published!' });
        } else {
            reject({ status: 500, message: 'Internal Server Error!' });
        }
    }); 
})};

Then, I'm going to get all the people who subscribed that kind of post. (Any user may have or not a filter on post's metadata)

exports.get_subscribers = function(req, res) { 
return new Promise((resolve,reject) => {
User.find({subscription: req.body.topic_type}, {'email': 1, 'queueName': 1, 'isFiltered': 1})
.then(users => {
        if (users.length == 0) {
            reject({ status: 404, message: 'Users Not Found!' });
        } else {
            //res.subscribers = {};
            res.subscribers = users;
            resolve({ status: 200, message: users });
        }
})
.catch(err => reject({ status: 500, message: 'Internal Server Error!' }));
})};

Finally, from the list of all the subscribers, I'm going to take just the one with a filter to apply it to the post's metadata and see if this user is interested in it. (User schema have email who has a references to Filter schema, so I'm going to do an aggregation between them to see if a user has a filter or not). If no one has a filter, I return the list of the subscribers without removing any, otherwise I'd remove the one not interested in the post). I'd still have to implement the remove part.

exports.apply_filter = function(req, res, subscribers)  {
var email_of_filters = [];

subscribers.forEach(function(value) {
        email_of_filters.push(value.email); 
});
console.log(email_of_filters);

return new Promise((resolve,reject) => {

    User.aggregate([
        {$project: {"email": "$email", "filter": "$filter"}},
        {$match: {isFiltered: {$ne: false}, email: {$in: email_of_filters}}},
        {$unwind: "$email"},
        {$lookup: 
            {from: "filters", localField: "email", foreignField: "email", as: "filter"}
        }
    ])

    .then(users_with_filters => {

        if (users_with_filters.length == 0) {
            resolve({ status: 200, message: subscribers });
        } else {
            reject({ status: 400, message: 'Error!' });
        }
    })
    .catch(err => reject({ status: 500, message: 'Internal server error!' }));
});
};

'get_subscribers' goes well if it is invoked alone. Same for 'create_a_topic'. Problem is encountered when invoking apply_filter.

Unhandled rejection rangerror: invalid status code: 0

I saw the following question on StackOverflow without resolving: 1, 2, 3. Any tip would be appreciated.

Route

app.post('/publish_topic', (req, res) => {
        project.create_a_topic(req, res)
            .then(result1 => {return project.get_subscribers(req, res);})
            .then(result2 => {return project.apply_filter(req, res, res.subscribers);})
            .then(result3 => {res.status(result3.status).json({ message: result3.message });})
            .catch(err => res.status(err.status >= 100 && err.status < 600 ? err.code : 500).send({message: err.message}))          
    });

Found the problem that is in the route: instead of

.catch(err => res.status(err.status >= 100 && err.status < 600 ? err.code: 500).send({message: err.message}))

I should have used

.catch(err => res.status(err.status >= 100 && err.status < 600 ? **err.status**: 500).send({message: err.message}))

So, problem is

err.code

instead of

err.status

BTW, I will follow your tips above. Thanks to all!