You can't use `macro parameter character #' in horizontal mode.

[bgrinstein]

Installed the package and run for a test the example given in the github (reproduced bellow). The result of compilation is the following error:

ERROR: You can't use `macro parameter character #' in horizontal mode.

--- TeX said ---
...inkstart {link}{\Hy@tocdestname }{##
######3}\hyper@linkend
l.2 \contentsline {chapter}{####3}{1}{chapter*.2}

--- HELP ---
The special character # has appeared in ordinary text. You probably
meant to type #.

Here is the full file I tried to compile:

\documentclass{book}
\usepackage[
% silent,% suppress the warning
% indentunnumbered% need unnumbered chapters to be indented in the toc??
]{unnumberedtotoc}
\usepackage{blindtext}
\begin{document}
\tableofcontents
\addchap{Wombat}
\addsec{Capybara}
\blindtext[10]
\chapter{Numbered chapter}
\addsec{unnumbered}
\section{numbered}
\end{document}