[tex4ht] another very strange problem using mathjax mode in tex4ht, footnote in table

[Nasser M. Abbasi]

After few hrs debugging, I found the case of this very strange problem.

Compiling this MWE

========================
\documentclass[12pt]{article}
\usepackage{longtable}
\begin{document}

\begin{longtable}{p{2in}}
    \footnote{this is foot note}
\end{longtable}
\end{document}
=================

When I compile using

make4ht -ulm default -a debug -c ./nma_mathjax.cfg foo3.tex "html,1,mathjax"

It fail with
=============================
(/usr/local/texlive/2020/texmf-dist/tex/latex/lm/ot1lmtt.fd)
! Use of \n:@xfootnotenext: doesn't match its definition.
\@ifnextchar ... \reserved at d =#1\def \reserved at a {
                                                   #2}\def \reserved at b {#3}\f...

l.9 \end{longtable}
=============================

Then found the cause in one line in my .cfg file above, which is

       hypergeom: ["\\operatorname{hypergeom}"]

When I comment the above line, then it compiles OK. I have no idea why that
is. The above line is part of my mathjax configuration which is
read when matjax loads. But why does it fail to compile even?

Please see my .cfg :  When commenting the line hypergeom: ["\\operatorname{hypergeom}"]
(and remember to remove the comma above it) then it compiles OK
-----------------------------
\Preamble{xhtml,p-width}
%V3.0 cobfiguration
\Configure{@HEAD}{\HCode{
<script>
window.MathJax = {
   tex: {
     maxBuffer: 40*1024,
     macros: {
         sp: "^",
         sb: "_",
       noalign: ["\#1", 1],
       medskip: "",
       hypergeom: ["\\operatorname{hypergeom}"] %comment this line out
     },
     autoload: {
       color: [],
       colorV2: ['color']
     },
     packages: {'[+]': ['noerrors']}
   },
   options: {
     ignoreHtmlClass: 'tex2jax_ignore',
     processHtmlClass: 'tex2jax_process'
   },
   loader: {
     load: ['[tex]/noerrors']
   }
};
</script>\Hnewline
}}
\begin{document}

\EndPreamble
--------------------------------------

Any idea why this happens?

For your convenience, I put the latex file and the above .cfg file in
this folder

https://www.12000.org/tmp/052220/

thanks
--Nasser