Закрыть подключение к mysql node.js

Где нужно закрыть подключение, чтобы скрипт не прервался? connection.end() вставлял после каждого query и всегда выводится ошибка

import config from './db/config.js'

const connection = await mysql.createConnection({
  host: config.host,
  database: config.mysqlMainDatabase,
  user: config.mysqlUser,
  password: config.mysqlPassword
})

const fillTables = async () => {
  const [result_1] = await connection.execute(`SELECT DISTINCT(f_1) FROM t_1`);
  result_1.map(async result_item => {
    await connection.execute(`INSERT INTO t_2 (f_1) VALUES (?)`, [result_item.m])
    const [result_mm] = await connection.execute(`SELECT DISTINCT(f_2) FROM t_1 WHERE f_1 = ?`, [result_item.m])
    let jsonM = []
    result_mm.map(async result_m => {
      jsonM.push(result_m.mm)
      const [result_ym] = await connection.query(`SELECT DISTINCT(f_3) FROM t_1 WHERE f_1 = ? AND f_2 = ?`, [result_item.m, result_m.mm])
      let jsonY = []
      result_ym.map(result_y => {
        jsonY.push(result_y.y)
      })
      await connection.query(`INSERT INTO t_3 (f_1, f_2, f_3) VALUES (?,?,?)`, [result_item.m, result_m.mm, JSON.stringify(jsonY)])
    })
    await connection.query(`INSERT INTO t_2 (f_1, f_2) VALUES (?,?)`, [result_item.m, JSON.stringify(jsonM)])
  })
}

await fillTables()```