Unhandled rejection RequestError: The conversion of the nvarchar value '238998679919674' overflowed an int column

I have table 'customers'

and table 'conversations'

I am pretty new in javascript. Currently, I try to use knex + bookshelf (SQL server database with tedious driver) to join those two tables. I separate those two tables in two models and call it from a router (I use Node js).

conversation.js

customer: function() {
  return this.belongsTo('Customer','uniqueid');
}

customer.js

conversation: function(){
  return this.hasMany('Conversation','customer_id');
}

When I try to join the tables as

Customer.fetchAll({withRelated:['conversation'], debug: true}).then(function(data{
  console.log('data : '+data);
});

Unfortunately, I always get the error:

Unhandled rejection RequestError: The conversion of the nvarchar value '238998679919674' overflowed an int column.

I curious about where is the error come from? since the columns' type is nvarchar, not int.

via Akmal