Loopback FindById returns null, not error when searching with a wrong Id

Question

I am struggling with the findById function of Loopback. When executing the function below with a non existing/wrong ID it returns an empty object/null and statuscode 200, not an error. When using the findById method in Loopback's explorer I receive an error message and 404 statuscode, as expected.

Can this be a bug inside Loopback? I can't imagine that I'll have to check if the result is empty every time. It should trow an error right?

Specs

• Loopback 3.18.1
• Mlab mongo db
• Node version 8.9.1

Loopback function inside a Models js file

Model.add = function(data, cb) {
let Vehicle = app.models.Vehicle;
Vehicle.findById('5b33a528b959503aeabf4827', function(err, vehicle) {
  if (err) {
    console.log(err);
  };
  cb(null, vehicle);
});
};

Answer 1

From the docs:

PersistedModel.findById(id, [filter], callback)

And for parameter callback the return instance is:

Model instance matching the specified ID or null if no instance matches.

https://apidocs.loopback.io/loopback/#persistedmodel-findbyid