Confluence Source Editor 1.1.2 stopped working in Confluence 5.9.1

Summary

Although the source editor plugin can be installed, when trying to edit the source code of a page I receive the following error:

Environment

• Confluence 5.9.1-OD-2015.47
• Confluence Source editor 1.1.2

Steps to Reproduce

1. Install Confluence 5.9.1-OD-2015.47 or above
2. Install Confluence source editor from the UPM

Expected Results

1. When editing a page, you can click on <> to edit source code

Actual Results

See attached image. Even if you paste the source code and click on 'Apply' nothing happens.

Notes

Might be related to Plugins 4

This was tested in Confluence 5.9.1-OD-2015.39.1-0001 with no issue.