node https module giving "error:0480006C:PEM routines::no start line" error, despite the certificates being correct

Outline

• I have generated a set of SSL certificates with certbot certonly for a domain (replaced with example.com here)
• I have an express server set up to use those certificates, there don't seem to be any issues reading the files, since they look right when I console.log them
• The certificate files, at least to my eye, look correctly formatted (with the correct headers & start lines)
• I am aware that similar questions exist, but in all of those that I could find, the issue is that the -----BEGIN CERTIFICATE----- and -----END CERTIFICATE----- lines were missing from the certificate & private key files, that doesn't seem to be the case here.

Problem

The https module is giving me the error error:0480006C:PEM routines::no start line when I try to start the server with https.

The Code

app.js

const express = require('express');const http = require('http');const https = require('https');const fs = require('fs');const { config } = require('dotenv');config();const app = express();const httpPort = process.env.HTTP_PORT;const httpsPort = process.env.HTTPS_PORT;try {  const privateKeyPath = process.env.SSL_KEY;  const publicKeyPath = process.env.SSL_CERT;  const privateKey = fs.readFileSync(privateKeyPath, 'utf8');  const certificate = fs.readFileSync(publicKeyPath, 'utf8');  const credentials = { key: privateKey, cert: certificate };  const httpsServer = https.createServer(credentials, app);  httpsServer.listen(httpsPort, () => {    console.log(`HTTPS Server listening on port ${httpsPort}`);  });} catch (ex) {  console.error('Certificates not found. Not using HTTPS');  console.error(ex);}const httpServer = http.createServer(app);httpServer.listen(httpPort, () => {  console.log(`HTTP Server listening on port ${httpPort}`);});

.env

HTTP_PORT=80HTTPS_PORT=443SSL_KEY=/etc/letsencrypt/live/example.com/fullchain.pemSSL_CERT=/etc/letsencrypt/live/example.com/privkey.pem

fullchain.pem

-----BEGIN CERTIFICATE----- ...base64 encoded text here-----END CERTIFICATE----------BEGIN CERTIFICATE----- ...base64 encoded text here-----END CERTIFICATE----------BEGIN CERTIFICATE----- ...base64 encoded text here-----END CERTIFICATE-----

privkey.pem

-----BEGIN PRIVATE KEY----- ...base64 encoded text here-----END PRIVATE KEY-----

Output

Certificates not found. Not using HTTPSError: error:0480006C:PEM routines::no start line    at node:internal/tls/secure-context:69:13    at Array.forEach (<anonymous>)    at setCerts (node:internal/tls/secure-context:67:3)    at configSecureContext (node:internal/tls/secure-context:156:5)    at Object.createSecureContext (node:_tls_common:117:3)    at Server.setSecureContext (node:_tls_wrap:1348:27)    at Server (node:_tls_wrap:1207:8)    at new Server (node:https:74:3)    at Object.createServer (node:https:112:10)    at Object.<anonymous> (/root/reponame/app.js:78:29) {  library: 'PEM routines',  reason: 'no start line',  code: 'ERR_OSSL_PEM_NO_START_LINE'}