Unable to get proper error messages from Passport Authentication

I have an APP where I am using Passport to authenticate and register users. I have set up mongoose validation for my schema.

For example:

    // # === Business Bio Validation === #
         var businessBioValidator = [
         validate({
         validator: 'isLength',
         arguments: [2, 140],
         message: 'Business Bio should be between 3 and 140 characters'
      })
      ];

And within my schema I have

      businessBio: {
             type: String,
             required: true,
             validate: businessBioValidator
         }, // only 140 characters

Now if this validation is not met I want to send the message in my validator as a Json response. If I put the code below within my actual "route" it works!

return provider.save(function (err) 
  {
    if (!err) {
      console.log("updated");
  } else
  {
      return res.send(err);
  }
  return res.send(provider);
});
});

But I can't send err response from my Passport authentication. See code below:

     function(req, email, password, done) {

    // asynchronous
    // User.findOne wont fire unless data is sent back

    process.nextTick(function() {
    console.log('using providers-signup passport');

    // find a user whose email is the same as the forms email
    // we are checking to see if the user trying to login already exists

      Provider.findOne({ 'email' :  email }, function(err, provider) {
        // if there are any errors, return the error
        if (err)
            return done(err);
        // check to see if theres already a user with that email
        if (provider) {
            return done(null, false, { message: 'User email already taken.'               
           });
             } else {

            // if there is no user with that email
            // create the user
            var newProvider            = new Provider();
            // CREATE USER HERE!

            // save the user
            newProvider.save(function(err) {
                if (err)
                {throw err;}
                return done(null, newProvider);
            }); }
            });
            });}));

Right now when I create a user through passport all my error are console logged on the node sever. How can I send the error messages from my passport authentication as JSON message response to the user.

Thanks in advance.