Remove usage of finally

See flarum/core@60d78ce

extensions/flags/js/forum/dist/extension.js

@@ -322,7 +322,7 @@ System.register('flarum/flags/components/FlagList', ['flarum/Component', 'flarum
               app.cache.flags = flags.sort(function (a, b) {
                 return b.time() - a.time();
               });
-            })['finally'](function () {
+            })['catch'](function () {}).then(function () {
               _this.loading = false;
               m.redraw();
             });
@@ -498,7 +498,7 @@ System.register('flarum/flags/components/FlagPostModal', ['flarum/components/Mod
               }
             }).then(function () {
               return _this.success = true;
-            })['finally'](this.loaded.bind(this));
+            })['catch'](function () {}).then(this.loaded.bind(this));
           }
         }]);
         return FlagPostModal;

extensions/flags/js/forum/src/components/FlagList.js

@@ -75,7 +75,8 @@ export default class FlagList extends Component {
         app.session.user.pushAttributes({newFlagsCount: 0});
         app.cache.flags = flags.sort((a, b) => b.time() - a.time());
       })
-      .finally(() => {
+      .catch(() => {})
+      .then(() => {
         this.loading = false;
         m.redraw();
       });

extensions/flags/js/forum/src/components/FlagPostModal.js

@@ -100,6 +100,7 @@ export default class FlagPostModal extends Modal {
       }
     })
       .then(() => this.success = true)
-      .finally(this.loaded.bind(this));
+      .catch(() => {})
+      .then(this.loaded.bind(this));
   }
 }