pandoc.WriterOptions does not complain if it is passed an uncompiled template

[fiapps]

The following Lua filter code is incorrect, because the template has not been compiled, but pandoc.WriterOptions does not throw an error for an invalid template value, it just silently ignores it and produces a non-standalone document. I consider it a bug that there is no error.

An alternative solution would be for pandoc.WriterOptions to try to compile the template if it is passed a string instead of a compiled template for template.

function write_markdown_file(doc, filename)
  local options = pandoc.WriterOptions{
    template = pandoc.template.default('markdown')
  }
  local data = pandoc.write(doc, 'markdown', options)
  local file <close>, error = io.open(filename, 'w')
  if file == fail then
    io.stderr:write(string.format('Failed to write Markdown file: %s\n', error))
    os.exit(1)
  end
  file:write(data)
end

I'm using pandoc 2.19.2 on macOS 12.6. See also the pandoc-discuss thread that led to filing this bug.