Error flash container is hidden when repeatedly updating issue

Summary

When user update the issue, the updating may fail due to backenderror(in the case of JH it maybe the content containing illegal words), and an error flash will be shown on the top of the page, and then if user continue to update the issue and the request still fail, the error flash will be hidden unexpectedly.

Steps to reproduce

First time updating issue, backend gave a response with error, error flash was shown:

Continue updating

backend gave a response with error again, but error flash was hidden, same with follow-up updating on current page unless user refresh the page:

flash-is-hidden

Example Project

What is the current bug behavior?

The error flash is hidden

What is the expected correct behavior?

The error flash should still be shown

Relevant logs and/or screenshots

Output of checks

Results of GitLab environment info

Expand for output related to GitLab environment info

(For installations with omnibus-gitlab package run and paste the output of:
`sudo gitlab-rake gitlab:env:info`)

(For installations from source run and paste the output of:
`sudo -u git -H bundle exec rake gitlab:env:info RAILS_ENV=production`)

Results of GitLab application Check

Expand for output related to the GitLab application check

(For installations with omnibus-gitlab package run and paste the output of:
sudo gitlab-rake gitlab:check SANITIZE=true)
(For installations from source run and paste the output of:
sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production SANITIZE=true)
(we will only investigate if the tests are passing)

Possible fixes