add user model

src/server/models/bookmark.js

@@ -47,7 +47,9 @@ module.exports = function(crowi) {
 
     return Bookmark.populate(bookmarks, {
       path: 'page',
-      populate: { path: 'lastUpdateUser', select: User.USER_PUBLIC_FIELDS, populate: User.IMAGE_POPULATION },
+      populate: {
+        path: 'lastUpdateUser', model: 'User', select: User.USER_PUBLIC_FIELDS, populate: User.IMAGE_POPULATION,
+      },
     });
   };