Error: ConnectionManager.getConnection was called after the connection manager was closed

I am trying to map values from one database to another database in Postgres using Sequelize. I encounter this error when running index.js file. I do not have another JS file other than this. Here is the code:

// Import Sequelize
const { Sequelize, DataTypes } = require('sequelize');
async function migrateData() {
// Define the connection to Database A
const dbA = new Sequelize('postgres', 'newuser', 'pass', {
  host: 'localhost',
  dialect: 'postgres'
});

// Define the connection to Database B
const dbB = new Sequelize('postgres2', 'newuser', 'pass', {
  host: 'localhost',
  dialect: 'postgres'
});

// Define the models for Database A and B
const ModelA = dbA.define('modelA', {
  id: {
    type: DataTypes.INTEGER,
    autoIncrement: true,
    primaryKey: true
  },
  name: {
    type: DataTypes.STRING,
    allowNull: false
  },
  age: {
    type: DataTypes.INTEGER,
    allowNull: false
  }
});

const ModelB = dbB.define('modelB', {
  student_id: {
    type: DataTypes.INTEGER,
    autoIncrement: true,
    primaryKey: true
  },
  student_name: {
    type: DataTypes.STRING,
    allowNull: false
  },
  student_age: {
    type: DataTypes.INTEGER,
    allowNull: false
  }
});

// Sync the models to their respective databases
dbA.sync();
dbB.sync();

// Map data from Database A to Database B
const dataFromA = await ModelA.findAll();
const mappedData = dataFromA.map(item => ({
  student_name: item.name,
  student_age: item.age
}))
ModelA.hasOne(ModelB);
ModelB.belongsTo(ModelA);


// Bulk insert the mapped data into Database B
await ModelB.bulkCreate(mappedData);

// Close the database connections
dbA.close();
dbB.close();
}

migrateData();

Before this, it gave me a async-await error which I resolved. But now this error. I can be completely wrong with my code. Error:

Error: ConnectionManager.getConnection was called after the connection manager was closed!
at ConnectionManager.getConnection. (file path blah blah)