A "serious" error is being reported for a line in jni/functions.html.

Here is the line, after being processed by pandoc.

<p><a id="ReleaseMode"></p>

In the HTML file it is line 2497, right before the table with the following caption: <caption>Primitive Array Release Modes</caption>

In functions.md, it is line 3112.

<a id="ReleaseMode">

Here's the details on the accessibility error:
https://dequeuniversity.com/rules/axe/3.0/link-name?application=webdriverjs

On the face of it, that is bad HTML, for being <a> without an </a>. Also, in HTML5, <a> is supposed to be for links, with the id being a global attribute that can be put on anything. Here we're dealing in Markdown, and there's no easy way(that I know) of to define an id on a table, which is what the pure-HTML solution would be. There's also no easy way in Markdown to define a "standalone" id. ids are typically defined as a side effect of headers.