gets converted into this html (please note the class="er" around "Fact", straight pandoc cmd with no options)

<div class="sourceCode" id="cb1"><pre class="sourceCode prolog"><code class="sourceCode prolog"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a>afact(<span class="ot">&quot;</span><span class="er">Fact</span><span class="ot">&quot;</span>)<span class="kw">.</span></span></code></pre></div>

and this latex (please note the ErrorTok{Fact})

\begin{Shaded}
\begin{Highlighting}[]
\NormalTok{afact(}\OtherTok{"}\ErrorTok{Fact}\OtherTok{"}\NormalTok{)}\KeywordTok{.}
\end{Highlighting}
\end{Shaded}

I am a complete Prolog noob, but that looks fine to me and SWI Prolog accepts it. Why is it marked as an error token? It results in a bold red font with pygments, quite eye-piercing. Thanks

Antonio