Fehler bei parskip=relative und pgfplots: TeX capacity exceeded

TeX capacity exceeded, sorry [grouping levels=255] \addplot[color=red]{-10 * x};

\documentclass[]{scrbook}
 
\RequirePackage{etex}
\usepackage{pgfplots}
 
\KOMAoptions{%
   parskip=relative, % change indentation according to fontsize (recommanded)
   parskip=false    % indentation of 1em
}%
 
\listfiles % list all loaded files at end of document
 
\begin{document}
\pgfplotsset{width=6cm}
\begin{tikzpicture}
\begin{axis}[
xlabel=Transmission $\eta$ / \%,
ylabel={Dämpfung / dB/cm}
]
%    use  TeX  as  calculator:
\addplot[color=red]{-10 * x};
\end{axis}
\end{tikzpicture}
\end{document}