Refined Toolkit theme is producing errors for specific users

Issue Summary

Some customers who have the Refined Toolkit for Confluence app installed and applied as a theme for spaces are reporting issues upon trying to access spaces using it.

This happens only with specific users in specific instances. Atlassian and Refined are not able to reproduce the issue.

Steps to Reproduce

1. Install the Refined Toolkit for Confluence app
2. Change the space settings and apply it as a theme (through Space settings > Look and feel > Themes)
3. Tap Confirm so the theme will be applied
4. Have a user accessing the space.

Expected Results

The space home page should be rendered properly.

Actual Results

The following issue is displayed:

Workaround

Affected users can temporarily revert to using the default Confluence `/wiki/spaces/choosetheme.action?key=SPACE`