Merge branch 'issue-boards-js-fix-backport' into 'master'

CE backport of issue-boards-js-fix

See merge request gitlab-org/gitlab-ce!20840

app/assets/javascripts/boards/index.js

-/* eslint-disable quote-props, comma-dangle */
-
 import $ from 'jquery';
 import _ from 'underscore';
 import Vue from 'vue';
@@ -47,7 +45,7 @@ export default () => {
   gl.IssueBoardsApp = new Vue({
     el: $boardApp,
     components: {
-      'board': gl.issueBoards.Board,
+      board: gl.issueBoards.Board,
       'board-sidebar': gl.issueBoards.BoardSidebar,
       BoardAddIssuesModal,
     },
@@ -65,11 +63,11 @@ export default () => {
       defaultAvatar: $boardApp.dataset.defaultAvatar,
     },
     computed: {
-      detailIssueVisible () {
+      detailIssueVisible() {
         return Object.keys(this.detailIssue.issue).length;
       },
     },
-    created () {
+    created() {
       gl.boardService = new BoardService({
         boardsEndpoint: this.boardsEndpoint,
         listsEndpoint: this.listsEndpoint,
@@ -89,15 +87,16 @@ export default () => {
       eventHub.$off('clearDetailIssue', this.clearDetailIssue);
       sidebarEventHub.$off('toggleSubscription', this.toggleSubscription);
     },
-    mounted () {
+    mounted() {
       this.filterManager = new FilteredSearchBoards(Store.filter, true, Store.cantEdit);
       this.filterManager.setup();
 
       Store.disabled = this.disabled;
-      gl.boardService.all()
+      gl.boardService
+        .all()
         .then(res => res.data)
-        .then((data) => {
-          data.forEach((board) => {
+        .then(data => {
+          data.forEach(board => {
             const list = Store.addList(board, this.defaultAvatar);
 
             if (list.type === 'closed') {
@@ -126,7 +125,7 @@ export default () => {
           newIssue.setFetchingState('subscriptions', true);
           BoardService.getIssueInfo(sidebarInfoEndpoint)
             .then(res => res.data)
-            .then((data) => {
+            .then(data => {
               newIssue.setFetchingState('subscriptions', false);
               newIssue.updateData({
                 subscribed: data.subscribed,
@@ -159,7 +158,7 @@ export default () => {
               Flash(__('An error occurred when toggling the notification subscription'));
             });
         }
-      }
+      },
     },
   });
 
@@ -168,13 +167,16 @@ export default () => {
     data: {
       filters: Store.state.filters,
     },
-    mounted () {
+    mounted() {
       gl.issueBoards.newListDropdownInit();
     },
   });
 
+  const issueBoardsModal = document.getElementById('js-add-issues-btn');
+
+  if (issueBoardsModal) {
     gl.IssueBoardsModalAddBtn = new Vue({
-    el: document.getElementById('js-add-issues-btn'),
+      el: issueBoardsModal,
       mixins: [modalMixin],
       data() {
         return {
@@ -241,4 +243,5 @@ export default () => {
         </div>
       `,
     });
+  }
 };