Errors on 172 are discarded, here.

Maybe change to

```go
armored, err := armor.Encode(w, "PGP MESSAGE", nil)
if err != nil {
    return err
}
plaintext, err := openpgp.Encrypt(armored,
                                  []*openpgp.entity{e.PGPkey},
                                  nil, nil, nil)
armored.Close()
if err != nil {
    return err
}
plaintext.Close()
// ...