BugFix for build:prod script

src/server/app.js

@@ -24,10 +24,10 @@ process.on('unhandledRejection', (reason, p) => {
 });
 
 growi.start()
-  .then(express => {
+  .then(server => {
     if (helpers.hasProcessFlag('ci')) {
       logger.info('"--ci" flag is detected. Exit process.');
-      express.close(() => {
+      server.close(() => {
         process.exit();
       });
     }

src/server/crowi/index.js

@@ -371,6 +371,8 @@ Crowi.prototype.start = async function() {
 
   // setup Express Routes
   this.setupRoutesAtLast(express);
+
+  return serverListening;
 };
 
 Crowi.prototype.buildServer = function() {