pandoc 2.9.2.1 on Arch Linux

git clone https://github.com/hakimel/reveal.js.git
wget https://pandoc.org/demo/SLIDES
pandoc -s --mathjax -i -t revealjs SLIDES -o example16d.html

produces output with the following error messages in Web Developer:

SyntaxError: import declarations may only appear at top level of a module (reveal.js:1)
ReferenceError: Reveal is not defined (example16d.html:75:7)

The example16d.html file itself looks like plain old HTML, with no CSS or JavaScript to speak of. I attach the entire folder to this issue.

I expected to get this.

pandoc-revealjs.tar.gz