Table of contents with manipulated subsections

Question

I got a brilliant solution to a question on how to manipulate the subsection to also be given by letters:

Numbering subsections, manually set letters or numbers

But, unfortunately I got an issue with the table of contents

\documentclass{article}
\usepackage{hyperref}
%\usepackage{letltxmacro}
\NewCommandCopy{\originalsubsection}{\subsection} %\LetLtxMacro{\originalsubsection}{\subsection} \RenewDocumentCommand{\subsection}{sd()O{#3}m}{%   \IfBooleanTF{#1}
    {\originalsubsection*{#4}}%
    {%
     \IfNoValueTF{#2}
       {% no letter
        \renewcommand{\thesubsection}{\thesection.\arabic{subsection}}%
       }
       {% letter
        \addtocounter{subsection}{-1}%
        \renewcommand{\thesubsection}{\thesection.#2}%
       }
     \originalsubsection[#3]{#4}%
    }% }
\renewcommand{\theHsubsection}{\thesubsection}
\begin{document}
\tableofcontents
\section{First section}
\subsection(P){First subsection}
\subsubsection{First subsubsection}
\subsubsection{Second subsubsection}
\subsection(V){Second subsection}\label{v}
\subsubsection{First subsubsection}\label{1-v}
\section{First section}
\subsection{First subsection}
\ref{v} and \ref{1-v}
\end{document}

The table of content looks like this:

Where NoValue is shown in the subsections with letters.

Any idea how to fix this? Thank you!

Answer 1

The third argument in the newly-defined \subsection should not use O{#3}, but instead o and then test whether #3 exists or not (using \IfValueTF{#3}{<true>}{<false>}). Here the <true> branch (if #3 was supplied) would use it as-is, otherwise (if #3) was not supplied) it should use #4.

\documentclass{article}
\usepackage{hyperref}
\NewCommandCopy{\originalsubsection}{\subsection} %\LetLtxMacro{\originalsubsection}{\subsection}
\RenewDocumentCommand{\subsection}{s d() o m}{%
  \IfBooleanTF{#1}
    {\originalsubsection*{#4}}%
    {%
     \IfValueTF{#2}
       {% letter
        \addtocounter{subsection}{-1}%
        \renewcommand{\thesubsection}{\thesection.#2}%
       }
       {% no letter
        \renewcommand{\thesubsection}{\thesection.\arabic{subsection}}%
       }%
     \originalsubsection[\IfValueTF{#3}{#3}{#4}]{#4}%
    }%
}
\renewcommand{\theHsubsection}{\thesubsection}
\begin{document}
\tableofcontents
\section{First section}
\subsection(P){First subsection}
\subsubsection{First subsubsection}
\subsubsection{Second subsubsection}
\subsection(V){Second subsection}\label{v}
\subsubsection{First subsubsection}\label{1-v}
\section{First section}
\subsection{First subsection}
\ref{v} and \ref{1-v}
\end{document}