Log GitHub OAuth authentication failure

lib/github-auth.js

@@ -1,5 +1,6 @@
 'use strict';
 
+const log = require('./log');
 const querystring = require('querystring');
 const request = require('request');
 const autosave = require('json-autosave');
@@ -44,6 +45,7 @@ function setRoutes(server) {
       return end('This server is missing GitHub client secrets.');
     }
     if (!data.code) {
+      log(`GitHub OAuth data.code: ${JSON.stringify(data)}`);
       return end('GitHub OAuth authentication failed to provide a code.');
     }
     const options = {