revision needs to be quoted to become a string

src/js/client.js

@@ -156,7 +156,7 @@ angular.module('Application').filter('markdown2html', function () {
 angular.module('Application').config(['$translateProvider', function ($translateProvider) {
     $translateProvider.useStaticFilesLoader({
         prefix: 'translation/',
-        suffix: '.json?' + <%= revision %>
+        suffix: '.json?' + '<%= revision %>'
     });
     $translateProvider.useLocalStorage();
     $translateProvider.preferredLanguage('en');