Merge branch 'fix-comment-race-condition' into 'master'

Fix race condition with polling when saving notes

Closes gitlab-ee#12472

See merge request gitlab-org/gitlab-ce!30724

app/assets/javascripts/notes/stores/actions.js

@@ -357,11 +357,11 @@ export const poll = ({ commit, state, getters, dispatch }) => {
 };
 
 export const stopPolling = () => {
-  eTagPoll.stop();
+  if (eTagPoll) eTagPoll.stop();
 };
 
 export const restartPolling = () => {
-  eTagPoll.restart();
+  if (eTagPoll) eTagPoll.restart();
 };
 
 export const fetchData = ({ commit, state, getters }) => {

changelogs/unreleased/fix-comment-race-condition.yml

+---
+title: Fix commenting before discussions are loaded
+merge_request: 30724
+author:
+type: fixed