UI bug in `User Settings > Account` (Chrome)

Summary

Chrome 72.0.3626.96 (Official Build) (64-bit) UI bug in User Settings > Account

Steps to reproduce

1. Go to user profile in top right corner, click Settings
2. Click Account from menu bar
3. Change username (to a name that is presumably unavailable), click `Update username'

Example Project

n/a

What is the current bug behavior?

Red bar appears sans text at top of screen

What is the expected correct behavior?

Presumably we would be informed that the username is no longer available

Relevant logs and/or screenshots

Output of checks

This bug happens on GitLab.com

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

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