The button for toggle-files-button doesn't show up #4547

Please ensure:

• The bug is caused by Refined GitHub. It doesn't happen if I disable the extension.

Describe the problem and how to replicate it

When the toggle-files-button feature is enabled, the button to toggle files is not shown, and only the README is visible.

This happens on every repo I've inspected, although admittedly they all had README files — I couldn't find a repo without a README to test against.

Screenshots/video/gif showing the issue, if it’s visual

With toggle-files-button disabled

With toggle-files-button enabled

Console errors, if any

No response

Example URL

https://github.com/evilphish/sennheiser-gsx-1000

Browser(s) used

Firefox 89.0.2, Windows 10