Conflict between JEditor and Insight Asset Management add-on

Symptoms

All possible icons are displayed on the JEditor's toolbar; changing toolbar settings in JEditor Configuration > Toolbar doesn't affect anything.

JEDITOR_CONFIGURATION_JIRA is undefined error appears in the browser console.

Cause

JEditor conflicts with a module of another add-on - Insight (Asset Management). This module is also an editor that loads its own configuration and breaks JEditor.

Possible workarounds

Disable the module that causes the conflict

1. Go to JIRA administration > Add-ons > Manage add-ons
2. Locate Insight - Asset Management and expand add-on's list of modules
3. Find module named CK Editor(ckeditor) and disable it

After that JEditor should start working properly. There will be a minor impact on Insight's textarea - it may be displayed as a plain text field or as a JEditor's instance.