Use NOT_IMPLEMENTED error code

src/dns/interface.js

@@ -17,6 +17,7 @@ exports = module.exports = {
 };
 
 var assert = require('assert'),
+    BoxError = require('../boxerror.js'),
     util = require('util');
 
 function removePrivateFields(domainObject) {
@@ -24,6 +25,7 @@ function removePrivateFields(domainObject) {
     return domainObject;
 }
 
+// eslint-disable-next-line no-unused-vars
 function injectPrivateFields(newConfig, currentConfig) {
     // in-place injection of tokens and api keys which came in with domains.SECRET_PLACEHOLDER
 }
@@ -80,5 +82,5 @@ function verifyDnsConfig(domainObject, callback) {
 
     // Result: dnsConfig object
 
-    callback(new Error('not implemented'));
+    callback(new BoxError(BoxError.NOT_IMPLEMENTED, 'verifyDnsConfig is not implemented'));
 }