fix(server): fix bundle serving path

src/app.js

@@ -17,6 +17,7 @@ const logger = require('@pubsweet/logger')
 
 const registerComponents = require('pubsweet-server/src/register-components')
 const api = require('pubsweet-server/src/routes/api')
+const index = require('pubsweet-server/src/routes/index')
 
 const configureApp = app => {
   const models = require('@pubsweet/models')
@@ -120,9 +121,7 @@ const configureApp = app => {
     config.has('pubsweet-server.serveClient') &&
     config.get('pubsweet-server.serveClient')
   ) {
-    app.get('*', (req, res) => {
-      res.sendFile(path.join('.', '_build', 'assets', 'index.html'))
-    })
+    app.use('/', index)
   }
 
   app.use((err, req, res, next) => {