header-includes in the YAML header causes an error when exporting to LaTeX or pdf

[tpellard]

When the YAML header contains header-includes, pandoc (2.13) cannot export to LaTeX or to pdf.
Exporting to docx works as expected.

Here is a minimal example and the command line run:

---
title: Testing pandoc-ling
header-includes: |
  \usepackage{hyperref}
---

# This is a test

::: ex
This is the most basic structure of a linguistic example.
:::

pandoc pandoc-ling_test.md -o pandoc-ling_test.tex --lua-filter pandoc-ling.lua

[cysouw]

I find the metadata handling of Pandoc confusing :-). But with a minimal change your problem has gone away. Please grab the latest commit for a working version.