I've noticed errors like this when using the extract package:

(\end occurred inside a group at level 1) ### semi simple group (level 1) entered at line 5 (\begingroup) 

This seems to happen even with an almost empty document, for example:

\documentclass{article} \usepackage[generate=foo.ext]{extract} \begin{document} Hello! \end{document} 

Would anyone have an idea why extract (extract 2019/09/18 v1.9a) is causing that error, and how to fix it?