How to fix the following underlined Arabic text?
\documentclass{article}
\usepackage[tuenc]{fontspec}
\newfontfamily\arabicfont{Amiri}[Script=Arabic, RawFeature={+anum}]
\usepackage{arabluatex}
\begin{document}
Without underlining:
\begin{txarab}
كتاب
\end{txarab}
With underlining
\begin{txarab}
\underline{كتاب}
\end{txarab}
\end{document}