Node.js & Mongoose: Async Function Logic

I'm writing an API for a project and recently we've shifted our technology stack to Node.js and MongoDB. However I could not settle some of the aspects related to Node and Mongo.

I started to code Node by checking the infamous Node Beginner tutorial, where it is highly mentioned to follow the non-blocking logic. That is if I understood correctly not waiting for a function to finish, but move on and later "magically" get the results of that function you've moved on.

But there is one thing that confused me which if the non-blocking is the essence of Node, should I follow it when I'm querying a database, because I have to assure and return the result of the connection as either success or the error. The code I have will explain better for the tl;dr 's; (by the way I'm using Mongoose as mongoDB ODM.

db.on('error', function(err){
        if(err)
            console.log("There is an error");
        response.write("Terrible Error!");
        response.end();
    });

I've written what to do when the db connection succeed after the 'db.on()' error code, however after a second thought I am think it is better to write in 'function(err)' since an error occurs it will directly cancel the operation and end the response. But is it against the non-blocking logic of Node.js?