Javascript error

@andras_szilagyi Hello

I followed your steps and placed the block on a page.

I found the same errors.
After reading the module instructions.
I found that
We need h tags with wrapper parent elements on the same page.

So, I added one block with custom code in CKEditor in the block layout.

<h2 id="section1">
    Section 1
</h2>
<p>
    Content for Section 1...
</p>
<h3 id="subsection2">
    Subsection 2
</h3>
<p>
    Content for Section 2...
</p>

and added its parent class ,h3,h2 tags in the configuration.

Then, I did not find any console errors, and the in-page navigation also started working.

Please check my attached screenshots.

Please update the parent class according to requirement and configurations mentioned in the screenshot