Steps to reproduce:
1) Create dashboard with widget - Map navigation tree.
2) Open another browser tab with master branch.
3) In second tab - navigate to Administration->Module.
4) Disable - Map navigation tree
5) In first browser tab (where created dashboard displayed and page still not reloaded) - press "edit" button on created widget.
6) Then try to add new Root.
7) On opened form - press "Add" button.

Result:
Console error.

Expected:
No errors. Can't press - "Add new root"