Refresh widget after canceling "Merge When Pipeline Succeeds"

Previously when a user clicked on "Cancel automatic merge", the merge
request widget store would fail with `currentUser is undefined` because
the `cancel_auto_merge` endpoint did not return user information.

Even after handling that problem, the merge request widget did not
refresh until waiting for a while. We fix this by forcing a refresh
after the cancellation is processed.

Closes https://gitlab.com/gitlab-org/gitlab/issues/197487

app/assets/javascripts/vue_merge_request_widget/components/states/mr_widget_auto_merge_enabled.vue

@@ -53,6 +53,7 @@ export default {
         .then(res => res.data)
         .then(data => {
           eventHub.$emit('UpdateWidgetData', data);
+          eventHub.$emit('MRWidgetUpdateRequested');
         })
         .catch(() => {
           this.isCancellingAutoMerge = false;

app/assets/javascripts/vue_merge_request_widget/stores/mr_widget_store.js

@@ -123,13 +123,15 @@ export default class MergeRequestStore {
 
     const currentUser = data.current_user;
 
-    this.cherryPickInForkPath = currentUser.cherry_pick_in_fork_path;
-    this.revertInForkPath = currentUser.revert_in_fork_path;
-
-    this.canRemoveSourceBranch = currentUser.can_remove_source_branch || false;
-    this.canCreateIssue = currentUser.can_create_issue || false;
-    this.canCherryPickInCurrentMR = currentUser.can_cherry_pick_on_current_merge_request || false;
-    this.canRevertInCurrentMR = currentUser.can_revert_on_current_merge_request || false;
+    if (currentUser) {
+      this.cherryPickInForkPath = currentUser.cherry_pick_in_fork_path;
+      this.revertInForkPath = currentUser.revert_in_fork_path;
+
+      this.canRemoveSourceBranch = currentUser.can_remove_source_branch || false;
+      this.canCreateIssue = currentUser.can_create_issue || false;
+      this.canCherryPickInCurrentMR = currentUser.can_cherry_pick_on_current_merge_request || false;
+      this.canRevertInCurrentMR = currentUser.can_revert_on_current_merge_request || false;
+    }
 
     this.setState(data);
   }

changelogs/unreleased/sh-refresh-mr-widget-upon-cancel.yml

+---
+title: Refresh widget after canceling "Merge When Pipeline Succeeds"
+merge_request: 26232
+author:
+type: fixed

spec/features/merge_request/user_merges_when_pipeline_succeeds_spec.rb

@@ -64,6 +64,10 @@ describe 'Merge request > User merges when pipeline succeeds', :js do
         before do
           click_button "Merge when pipeline succeeds"
           click_link "Cancel automatic merge"
+
+          wait_for_requests
+
+          expect(page).to have_content 'Merge when pipeline succeeds', wait: 0
         end
 
         it_behaves_like 'Merge when pipeline succeeds activator'