Prevent console error with Mongoose, node and graphql

I'm making an API server with Express, Graphql (Apollo server) and mongoose.

I'm testing the user creation. When the email is duplicated mongoose throws an error (Validation error. Unique = true) and graphql handles very good. But the console (terminal) shows the error too. How can i prevent that issue?

Resolver:

const MODEL_PATH = '../../models';
const User = require(MODEL_PATH + '/User');
const { register } = require('../../controllers/auth/RegisterController');
module.exports = {
  RootQuery: {
    users() {
      return User.find({});
    }
  },
  Mutation: {
    registerUser(_, data) {
      return register(data);
    }
  }
};

RegisterController (register function)

exports.register = function(data) {
  const { email, password } = data;
  const user = new User({
    email,
    password
  });
  return new Promise((resolve, reject) => {
    user.save().then((user) => {
      resolve(user);
    }).catch((err) => {
      reject(err);
    });
  });
};

And the error in the console (I DON'T WANT THAT. I HANDLED THE ERROR IN THE CONTROLLER. I WANT THE ERROR ONLY IN THE GRAPHQL RESPONSE)

MongoError: E11000 duplicate key error collection: y.users index: email_1 dup key: { : "test@example.com" }
    at Function.MongoError.create (/Volumes/Datos/x/code/y/server/node_modules/mongodb-core/lib/error.js:31:11)
    at toError (/Volumes/Datos/x/code/y/server/node_modules/mongodb/lib/utils.js:114:22)
   ....

Response in Graphiql (That is ok)

{
  "data": {
    "registerUser": null
  },
  "errors": [
    {
      "message": "E11000 duplicate key error collection: y.users index: email_1 dup key: { : \"test@example.com\" }",
      "locations": [
        {
          "line": 9,
          "column": 3
        }
      ],
      "path": [
        "registerUser"
      ]
    }
  ]
}

Thank you