I need to save a certificate in both PEM and DER encoding.
PEM is not an issue:

const cert = forge.pki.createCertificate();
// (...)
// (...)
// cert.sign(...);
const pemCert = forge.pki.certificateToPem(cert);
fs.writeFileSync('cert.pem', pemCert, {encoding: 'utf-8'});
// ^ GOOD

DER on the other hand, I cannot figure out how to save the proper certificate to file.

I would expect the following JS code to match the output of
openssl x509 -outform der -in ./cert.pem -out ./cert_good.cer,
however that is not the case and I get something different, apparently “malformed”:

const derCert = forge.pki.pemToDer(pemCert).getBytes();
fs.writeFileSync('cert_bad.cer', derCert, {encoding: 'utf-8'});

When I say “malformed” I refer to the fact that
openssl x509 -inform der -in cert_bad.cer -text -noout returns:
Could not find certificate from cert_bad.cer

What am I doing wrong?
ty

EDIT
I figured another way around this, using Node.js Crypto moudule -> class X509Certificate -> property raw.
Yet the question about node-forge remains. Anyway:

import { X509Certificate } from 'crypto'

const cert = forge.pki.createCertificate();
// (...)
// (...)
// cert.sign(...);
const pemCert = forge.pki.certificateToPem(cert);
fs.writeFileSync('cert.pem', pemCert, {encoding: 'utf-8'});
// ^ GOOD

const x509 = new X509Certificate(pemCert);
const derCert = x509.raw;
fs.writeFileSync('cert_good.cer', derCert, {encoding: 'utf-8'});
// ^ NOW ALSO GOOD