Error when using more than two affiliations

I tried using the new \affil macro, which works fine if there are only two affiliations (like in lni-paper-example-de.tex). However, if I add a third affiliation, building the document fails. Here is a minimal example:

\documentclass{lni}

\begin{document}

\title{Titel}

\author[1]{Vorname1 Nachname1}{vorname1.name1@affiliation1.de}{0000-0000-0000-0000}
\author[2]{Vorname2 Nachname2}{vorname2.name2@affiliation2.de}{0000-0000-0000-0000}
\author[3]{Vorname3 Nachname3}{vorname3.name3@affiliation3.de}{0000-0000-0000-0000}
\affil[1]{Universität\\Abteilung\\Straße\\Postleitzahl Ort\\Land}
\affil[2]{University\\Department\\Address\\Country}
\affil[3]{University\\Department\\Address\\Country}
\maketitle

\end{document}

It fails with the following error log (some lines omitted):

This is pdfTeX, Version 3.141592653-2.6-1.40.25 (MiKTeX 23.10.12) (preloaded format=pdflatex 2023.11.28)  29 NOV 2023 08:04
entering extended mode
 restricted \write18 enabled.
 %&-line parsing enabled.
**./main.tex
(main.tex
LaTeX2e <2023-11-01>
L3 programming layer <2023-11-09>
(lni.cls
Document Class: lni 2023/11/26 v1.8 Official class for submissions to the ``Lec
ture Notes in Informatics''
(C:\Program Files\MiKTeX\tex/generic/iftex\iftex.sty
Package: iftex 2022/02/03 v1.0f TeX engine tests
)

...

! LaTeX Error: There's no line here to end.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
 ...                                              

l.14 

? X

If I remove the line with \affil[3] and the reference to it, everything works fine.

gi-ev / LNI

Error when using more than two affiliations #148