babel (french) clash with xcolor : Error: Undefined color

[flomine]

When included, babel package (with french option) induced an error with xcolor.
For example, considering this working example:

\documentclass[handout]{beamer}
%\usepackage[french]{babel}%<----- When included, this line induces error
\usepackage[dvipsnames]{xcolor}
\usepackage{nicematrix}
\begin{document}

\begin{frame}{A test}
\sffamily
\renewcommand{\arraystretch}{1.4}

\begin{center}
\begin{NiceTabular}
   [
     columns-width=3cm,
     hvlines-except-borders,
     rules={color=white,width=1pt}
   ]
   {ccc}
\CodeBefore
  \rowcolor{NavyBlue}{1}
  \rowcolors{2}{NavyBlue!25}{NavyBlue!15}
\Body
  \RowStyle[color=white]{}
  First column & Second column & Third column \\
  1            & A             & E            \\
  2            & B             & F            \\
  3            & C             & G            \\
  4            & D             & H            \\
\end{NiceTabular}
\end{center}
\end{frame}
\end{document}

If you add this "\usepackage[french]{babel}", then we have the error
Package xcolor Error: Undefined color NavyBlue\penalty @m \hskip .5\fontdimen 2\font \relax '.`

[davidcarlisle]

It is I think specifically withthe way nicematrix re-executes the code, you can use

  \rowcolors{2}{NavyBlue\string!25}{NavyBlue\string!15}

[u-fischer]

it is a nicematrix problem. It expands the color name (imho in \__nicematrix_add_to_colors_seq:ee) without babel protection. You can try with

\CodeBefore
  \csname @safe@activestrue\endcsname
  \rowcolor{NavyBlue}{1}
  \rowcolors{2}{NavyBlue!25}{NavyBlue!15}
\Body