Nodejs 连接 mysql时报Error: Cannot enqueue Query after fatal error错误的处理办法

npm install mysql --save

//导入mysql连接包
const mysql = require('mysql');
let dbconfig ={
    host: 'db_host',
    user: 'db_user',
    password: 'db_pass',
    database: 'db_name',
    debug: true
};
function handleDisconnection() {
    db = mysql.createConnection(dbconfig);
    db.connect(function (err) {
        if (err) {
            console.log('db connect error:' + err.message + "2秒后重连");
            setTimeout(handleDisconnection, 2000);
        }
    });
    db.on('error', function (err) {
        console.log(err);
        if (err.code === 'PROTOCOL_CONNECTION_LOST') {
            console.log('db error执行重连:' + err.message);
            handleDisconnection();
        } else {
            throw err;
        }
    });
    db.querySync = function(sql) {
        return new Promise(function(resolve, reject) {
            db.query(sql, function(error, results, fields) {
                if(error) reject(error);
                else resolve({results, fields})
            })
        })
    };
    return db;
}
//创建连接conn
exports.db = handleDisconnection();

let dbconfig ={
    host: 'db_host',
    user: 'db_user',
    password: 'db_pass',
    database: 'db_name',
    debug: true
};

let dbconfig ={
    host: 'db_host',
    user: 'db_user',
    password: 'db_pass',
    database: 'db_name',
    useConnectionPooling: true,
    debug: true
};