Failure with error when markdown headings exist

[rahji]

The following error occurs when trying to run the Docker container with a letter.md that has 2nd-level headings in it. I didn't try other levels of headings - I just assumed the same issue would occur.

Error producing PDF.
! Undefined control sequence.
l.88 \subsection

[tjex]

also trying to solve this. I got part way by including the \usepackage{titlesec}. The error got less broad at least. But haven't gotten further so far.

Subheadings work with the default pandoc template, but I cant actually figure out where that functionality is being included. I thought \usepackage{pgfpages}, but just including that doesn't change much.

[tjex]

Looks like sections aren't included in the letter class :(

https://tex.stackexchange.com/questions/65962/sectioning-in-letter-type-documents