Try to fix Duplicate Board.

Thanks to xet7 !

Fixes #4459

client/components/boards/boardsList.js

@@ -239,7 +239,7 @@ BlazeComponent.extendComponent({
             },
             (err, res) => {
               if (err) {
-                this.setError(err.error);
+                self.setError(err.error);
               } else {
                 Session.set('fromBoard', null);
                 subManager.subscribe('board', res, false);

models/cards.js

@@ -4,6 +4,8 @@ import {
   TYPE_LINKED_BOARD,
   TYPE_LINKED_CARD,
 } from '../config/const';
+import Attachments from "./attachments";
+
 
 Cards = new Mongo.Collection('cards');
 
@@ -585,8 +587,8 @@ Cards.helpers({
     // Copy attachments
     oldCard.attachments().forEach(att => {
       att.cardId = _id;
-      Attachments.insert(att);
       delete att._id;
+      return Attachments.insert(att);
     });
 
     // copy checklists