Steps to reproduce the issue

during PR, the following error is occurred on drone CI

+-- karma-firefox-launcher@0.1.7
+-- karma-jasmine@0.3.8
+-- karma-jasmine-ajax@0.1.13
| -- jasmine-ajax@3.4.0 +-- karma-requirejs@1.1.0 +-- karma-verbose-reporter@0.0.3 +-- requirejs@2.3.5-- text@2.0.15 (git://github.com/requirejs/text.git#d04de4ffd7bf5ba6cb80cdca2d40d4f6f52a1b1f)

npm WARN optional Skipping failed optional dependency /chokidar/fsevents:
npm WARN notsup Not compatible with your operating system or architecture: fsevents@1.2.4

• cd ../..
• tests/javascript/node_modules/karma/bin/karma start karma.conf.js --single-run
  29 06 2018 04:55:38.574:INFO [karma]: Karma v0.13.22 server started at http://localhost:9876/
  29 06 2018 04:55:38.611:INFO [launcher]: Starting browser Firefox
  29 06 2018 04:55:41.740:INFO [Firefox 59.0.0 (Ubuntu 0.0.0)]: Connected on socket EY7l9dHm9rBG3zU7AAAA with id 20438334
  29 06 2018 04:55:44.284:ERROR [Firefox 59.0.0 (Ubuntu 0.0.0)]: TypeError: a.ui is undefined
  at http://localhost:9876/base/media/jui/js/jquery.ui.sortable.min.js?3ebfa0c205cdb3b90e6858aea5c05607b57e93c8:17

Suites and tests results:

Browser results:

Expected result

No errors expected

Actual result

System information (as much as possible)

Additional comments

I have not modified any javascript files on PR.