TypeError: Cannot set property 'email' of undefined

var toUpdate = {};

if (data.firstname) toUpdate.firstname = data.firstname;
if (data.lastname) toUpdate.lastname = data.lastname;
if (data.email) {
    toUpdate.email = data.email;
    toUpdate.local.email = data.email;
}
if (data.password !== '') toUpdate.local.password = user.generateHash(data.password);
if (data.role) toUpdate.role = data.role;
...
if (data.apiKey) toUpdate.api_key = data.apiKey;
if (data.active) toUpdate.active = data.active;

dbUser.update({'_id' : data.id}, toUpdate, {upsert : true}, function (err) {
    if (err) return callback(new Error(err));
    callback(null, data.id);
});

dbUser.findbyId(data.id, function(err, user){
  if(err){
    return callback(err);
  }
  if(!user){
    user = new dbUser();
  }
  if (data.firstname) user.firstname = data.firstname;
  //...//
  if(data.email){
     user.local = user.local || {};
     user.local.email = data.email;
  }
  if(data.password !== '') {
    user.local = user.local || {};
    user.local.password = dbUser.generateHash(data.password);
  }
  user.save(callback);
});