Im trying to configure master slave in nodejs web. I want to connect to the slave server when the master one is collapsed. I tried to stop the master and it really connected to the slave. However, when i signed in on the web, the web crashed. How should i fix this?

Here is the code

let db = null;


function createDatabaseConnection() {
  if (!db) {
    db = mysql.createConnection(master);

    db.on('error', (err) => {
      console.error('Cant connect to master server:', err);
      console.log('Change to slave server.');
        db = mysql.createConnection(slave);
        reconnect(db);
    });
  }

  return db;
}

function reconnect(connection) {
  connection.connect((err) => {
    if (err) {
      console.error('Cant connect to slave server:', err);
    } else {
      console.log('Connected to slave server.');
    }
  });

  connection.on('error', (err) => {
    console.error('Cant connect to slave server:', err);
  });
}

module.exports = createDatabaseConnection();

Here is the error

Cant connect to master server: AggregateError
    at internalConnectMultiple (node:net:1114:18)
    at afterConnectMultiple (node:net:1667:5) {
  code: 'ECONNREFUSED',
  fatal: true,
  [errors]: [
    Error: connect ECONNREFUSED ::1:3306
        at createConnectionError (node:net:1634:14)
        at afterConnectMultiple (node:net:1664:40) {
      errno: -4078,
      code: 'ECONNREFUSED',
      syscall: 'connect',
      address: '::1',
      port: 3306
    },
    Error: connect ECONNREFUSED 127.0.0.1:3306
        at createConnectionError (node:net:1634:14)
        at afterConnectMultiple (node:net:1664:40) {
      errno: -4078,
      code: 'ECONNREFUSED',
      syscall: 'connect',
      address: '127.0.0.1',
      port: 3306
    }
  ]
}
Change to slave server.
Connected to slave server.
[]
C:UsersAdminsourcereposHotelBookingnode_modulesmysql2libconnection.js:164
    const err = new Error(
                ^

Error: Can't add new command when connection is in closed state