Even the most trivial example fails.
Here's the main file, test.tex:
\documentclass[10pt]{combine}
\usepackage{combinet}
\begin{document}
\pagestyle{combine}
\clearpage
\begin{papers}
\import{a1}
\end{papers}
\end{document}
The the tex file to import into the main document, a1.tex (in same folder):
\documentclass{article}
\author{Author}
\title{Title}
\begin{document}
\maketitle
\end{document}
No matter what I try, it does not compile, generating the following error:
This is pdfTeX, Version 3.141592653-2.6-1.40.24 (MiKTeX 21.12) (preloaded format=pdflatex.fmt)
restricted \write18 enabled.
entering extended mode
(C:/Users/vince/tex/MLbook/test.tex
LaTeX2e <2021-11-15> patch level 1
L3 programming layer <2021-11-22>
(C:\Users\vince\AppData\Local\Programs\MiKTeX\tex/latex/combine\combine.cls
Document Class: combine 2010/07/10 v0.7a collection of documents
(C:\Users\vince\AppData\Local\Programs\MiKTeX\tex/latex/graphics\keyval.sty)
(C:\Users\vince\AppData\Local\Programs\MiKTeX\tex/latex/base\article.cls
Document Class: article 2021/10/04 v1.4n Standard LaTeX document class
(C:\Users\vince\AppData\Local\Programs\MiKTeX\tex/latex/base\size10.clo)))
(C:\Users\vince\AppData\Local\Programs\MiKTeX\tex/latex/combine\combinet.sty)
! Extra \endgroup.
\document ->\endgroup
\let \mainjobname \jobname \def \c@lmainauxfile {\jobn...
l.4 \begin{document}
?