问从Node.js应用程序查询Heroku托管Postgres数据库时出现‘'Self certificate’错误

EN

(node:2100) UnhandledPromiseRejectionWarning: Error: self signed certificate
    at TLSSocket.onConnectSecure (_tls_wrap.js:1051:34)
    at TLSSocket.emit (events.js:189:13)
    at TLSSocket._finishInit (_tls_wrap.js:633:8)
(node:2100) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)
(node:2100) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
D:\MY\DEV\PROJECTS\AdsSubscribeBot\test.js:57
  if (err) throw err;
           ^

Error: Connection terminated unexpectedly
    at Connection.con.once (D:\MY\DEV\PROJECTS\AdsSubscribeBot\node_modules\pg\lib\client.js:264:9)
    at Object.onceWrapper (events.js:277:13)
    at Connection.emit (events.js:189:13)
    at Socket. (D:\MY\DEV\PROJECTS\AdsSubscribeBot\node_modules\pg\lib\connection.js:76:10)
    at Socket.emit (events.js:194:15)
    at TCP._handle.close (net.js:597:12)

const connectionString = 'postgres://USERNAME:PASSWORD@HOST:PORT/DB_NAME';

const { Client } = require('pg');

const client = new Client({
  connectionString: connectionString,
  ssl: true
});

client.connect();

client.query('SELECT * FROM users;', (err, res) => {
  if (err) throw err;
  for (let row of res.rows) {
    console.log(JSON.stringify(row));
  }
  client.end();
});