openpgp/packet: fix swallowed errors in (*EncryptedKey).parse

Change-Id: I23da7bcda044417804a4c827501437d506002e8e
Reviewed-on: https://go-review.googlesource.com/63430
Run-TryBot: Filippo Valsorda <filippo@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Filippo Valsorda <filippo@golang.org>

openpgp/packet/encrypted_key.go

@@ -42,12 +42,18 @@ func (e *EncryptedKey) parse(r io.Reader) (err error) {
 	switch e.Algo {
 	case PubKeyAlgoRSA, PubKeyAlgoRSAEncryptOnly:
 		e.encryptedMPI1.bytes, e.encryptedMPI1.bitLength, err = readMPI(r)
+		if err != nil {
+			return
+		}
 	case PubKeyAlgoElGamal:
 		e.encryptedMPI1.bytes, e.encryptedMPI1.bitLength, err = readMPI(r)
 		if err != nil {
 			return
 		}
 		e.encryptedMPI2.bytes, e.encryptedMPI2.bitLength, err = readMPI(r)
+		if err != nil {
+			return
+		}
 	}
 	_, err = consumeAll(r)
 	return