refactor: keygen: refactor same expression (#16)

This commit refactors same expression in keygen.go.

Signed-off-by: orangekame3 <[email protected]>

keygen.go

@@ -473,11 +473,8 @@ func (s *KeyPair) WriteKeys() error {
 	if memo := pubKeyMemo(); memo != "" {
 		ak = fmt.Sprintf("%s %s", ak, memo)
 	}
-	if err := writeKeyToFile([]byte(ak), s.publicKeyPath()); err != nil {
-		return err
-	}
 
-	return nil
+	return writeKeyToFile([]byte(ak), s.publicKeyPath())
 }
 
 // KeyPairExists checks if the SSH key pair exists on disk.