Minor fix.

Author: sjudson

lib/key/private.js

@@ -190,7 +190,7 @@ function _public(cb) {
   const pk = new PublicKey(self.protocol());
 
   // we don't have to check sodium first because we wouldn't have this private key without it
-  const rkey = (self.protocol instanceof V1)
+  const rkey = (self.protocol() instanceof V1)
         ? extcrypto.extract(self.raw())
         : Buffer.from(sodium.crypto_sign_ed25519_sk_to_pk(self.raw()));