Cannot connect with dev database due to SSL issue

I’m using DigitalOcean App Platform to host a small node.js app. For the time being, I decided to go with the dev database that happens to be PostgreSQL. I understand it’s not meant to be used in production, but does that mean the app cannot connect to it remotely?

I’m using the pg package to create the database client.

const db_config = {
  user: process.env.PGUSER,
  password: process.env.PGPASSWORD,
  host: process.env.PGHOST,
  database: process.env.PGDATABASE,
  port: process.env.PGPORT,
  ssl: true
}

const client = new Client(db_config);
client.connect();

However, when that code executes, it returns the following:

(node:1) UnhandledPromiseRejectionWarning: Error: self signed certificate in certificate chain
     at TLSSocket.onConnectSecure (_tls_wrap.js:1502:34)
     at TLSSocket.emit (events.js:314:20)
     at TLSSocket._finishInit (_tls_wrap.js:937:8)
     at TLSWrap.ssl.onhandshakedone (_tls_wrap.js:711:12)
(node:1) 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(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
(node:1) [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.

I’m not sure how to get around that. I’m specifying the SSL option in the config. Can anyone help?