Fix transient job failures relating to "unhandled Promise rejection" in issue boards

What does this MR do?

Adds proper error handling to failed AJAX requests

Are there points in the code the reviewer needs to double check?

all tests should pass

Why was this MR needed?

Changes in !9846 (merged) now block AJAX requests generated by javascript after an RSpec test is completed waiting for already-pending requests to finish, it would catch the errors these failing requests where they previously would have been ignored.

Screenshots (if relevant)

n/a

Does this MR meet the acceptance criteria?

• [ ] Changelog entry added, if necessary
• [ ] Documentation created/updated
• [ ] API support added
• Tests
  • [ ] Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #32030 (closed)

Is this happening in our 9-2-stable branch as well? Should I Pick into Stable?

EE Port is at gitlab-ee!1858

Awesome, thanks a lot @mikegreiling!

added 1 commit

• 8d61bbcf - add proper error handling to failed ajax requests in the issue boards

Compare with previous version

resolved all discussions

added 1 commit

• 8d61bbcf - add proper error handling to failed ajax requests in the issue boards

Compare with previous version

added 1 commit

• fdfc462c - add proper error handling to failed ajax requests in the issue boards

Compare with previous version

added 1 commit

• fb7c9401 - stub error handlers where uncaught Promise rejections currently exist

Compare with previous version

ok, I ended up reverting my changes and starting over... using Flash messages was a naive approach. I've taken the more conservative approach and just stubbed the error handlers so they can be properly dealt with later (preferably by @iamphill or somebody who is more familiar with the issue boards in general)

mentioned in merge request !11171 (merged)

alright, this is finally green. @iamphill can you review/merge this?

assigned to @iamphill

this has been merged into EE via gitlab-ee!1837 so all it might be prudent to get this in soon before EE conflicts arise in the next ce-to-ee merge

resolved all discussions

mentioned in issue #32062 (moved)

LGTM, Thanks @mikegreiling

marked the checklist item All builds are passing as completed

approved this merge request

merged

mentioned in commit a6eaa51c

@mikegreiling This needs a milestone, otherwise it will never be picked up by a release manager!

changed milestone to %9.2

@mikegreiling Thanks for the fix, btw! 🎉

assigned to @mikegreiling

mentioned in commit c3fa0b62

Picked into 9-2-stable, will go into 9.2.0-rc1.

mentioned in issue #31934 (closed)

mentioned in issue gitlab#9750