PGP key decryption Error with openpgp - TypeError: Cannot read property 'type' of null at SecretKey.decrypt

Question

I am trying to decrypt one PGP file with OpenPGP javascript library. I am getting one error on the private key decryption

TypeError: Cannot read property 'type' of null at SecretKey.decrypt

Here is my code snippet

    let privateKey = (await openpgp.key.readArmored(this.pgpConfig.privateKey));
    if (!privateKey.keys[0]) {
        throw privateKey.err[0];
    } else {
        privateKey = privateKey.keys[0];
    }
    await privateKey.decrypt(this.pgpConfig.passphrase);

Getting error from await privateKey.decrypt(this.pgpConfig.passphrase); line.

I tried to decrypt a file with another online tool and it seems to work fine over there. So any idea what could be the issue here.

FYI I have generated keys from Kleopatra software.