How can I get `\texttt` in `\href` to work with Springer Nature's sn-jnl class?

Question

Using version 2019/11/18 of Springer's sn-jnl.cls template (archived as a gist here), I get the following:

\documentclass{sn-jnl}
\usepackage{xparse}
\NewDocumentCommand{\githublink}{m m o}{\href{}{\texttt{}}}
\begin{document}
. \githublink{}{}[]
\end{document}

! Argument of \XKV@d@fine@k@y has an extra }.
<inserted text>
                \par
l.5 . \githublink{}{}[]

What's going on here, and how do I fix this?

EDIT

This can be further minimized to

\documentclass{article}
\RequirePackage{hyperref}%
%%\RequirePackage{hypcap}%
\gdef\breakurldefns{%
%\if@pdflatex\else%
  \RequirePackage[hyphenbreaks]{breakurl}%
  \let\href\burlalt%
  %\fi
}%
\breakurldefns%
%    \bgroup
\usepackage{hyperref}
\begin{document}
. \href{}{\texttt{}}
\end{document}

Answer 1

The breakurl package shouldn't be used with pdflatex, but to avoid that it is loaded you must load the class with the option pdflatex as the class is a bit dump and doesn't make use of existing methods to detect the output mode automatically.

\documentclass[pdflatex]{sn-jnl}
\begin{document}

\href{abc}{\texttt{abc}}
\end{document}

Answer 2

If you try

\documentclass{article}
\usepackage{hyperref}
\usepackage[hyphenbreaks]{breakurl}
\begin{document}

. \burlalt{aaaa}{bbb}
\end{document}

You get

so the first argument is typeset, you can use font changes there. The second argument is the URL