AODA/WCAG - Accessibility Bar assistance

Hello everyone,

I have been spinning my wheels here as I am still learning websites. I have custom code (which you may use) to add a free accessibility bar to your website.

I am having a hard time linking all the code needed.

Here are some links for you:

Example (Demo) site:
https://www.cssscript.com/demo/sliding-accessibility-settings-panel/

The instructions I am using.

My public Github: GitHub - TheMarketingGuru/Accessibility: Accessibility plugin repo

Header tags:

Current error:
asb.js:88 Uncaught TypeError: Cannot read property ‘insertBefore’ of null
at asb.js:88
at asb.js:426

(link to specific code error: https://combinatronics.com/TheMarketingGuru/Accessibility/main/Accessibility-Settings-Bar-master/src/js/asb.js)

Practise site:
https://preview.webflow.com/preview/bingoproject?utm_medium=preview_link&utm_source=dashboard&utm_content=bingoproject&preview=42b5414170a23072d467c2504c24f310&workflow=preview