Fixed integration edit page not showing after creating new integration

refs 054a5f15f5

- `beforeClose` behaviour has changed slightly with the upgraded ember-promise-modals
- added a guard for the modal existing when transitioning back to the integrations index screen, this makes sure we're not transitioning back to the index screen after the modal has already initiated a transition to the integration edit screen

ghost/admin/app/routes/settings/integrations/new.js

@@ -5,6 +5,7 @@ import {inject as service} from '@ember/service';
 export default class NewIntegrationRoute extends AdminRoute {
     @service limit;
     @service modals;
+    @service router;
 
     modal = null;
 
@@ -38,8 +39,8 @@ export default class NewIntegrationRoute extends AdminRoute {
 
     @action
     beforeModalClose() {
-        if (!this.isLeaving) {
-            this.transitionTo('settings.integrations');
+        if (this.modal && !this.isLeaving) {
+            this.router.transitionTo('settings.integrations');
         }
     }
 }