Hi, I'm new to lua, so forgive me if this is something basic.

I'm trying to create a filter to convert the text "{{pagebreak}}" into a docx page break. I know there are existing haskel filters for this, and that I could also use a raw block directly in my docx (I've done that already) but I wanted to scratch my itch and do it with a lua filter.

So far trying different approaches I have ended up with:

-- file: macro-expander.lua

function pagebreak_to_docx (inlines)

  if #inlines ~= 1 then return end
  if inlines[1].t == 'Str' and inlines[1].text == "{{pagebreak}}" then
    return pandoc.RawBlock{"openxml", "<w:p><w:r><w:br w:type=\"page\"/></w:r></w:p>"}
  end
end

  function Para (c)
    return pagebreak_to_docx(c.content)
  end

Still when I run it with a basic example, I get the following error:

Could not read list: Could not get Block value: Expected a string but got a nil

Right at the exact place where the {{pagebreak}} occurs.

Without the filter:

$ echo -e "Raw Block in md: \n\n\`\`\`{=openxml}\n<w:p>\n\`\`\` \n\nLua Filter Test: \n\n{{pagebreak}}" | pandoc -f markdown -t native
[Para [Str "Raw",Space,Str "Block",Space,Str "in",Space,Str "md:"]
,RawBlock (Format "openxml") "<w:p>"
,Para [Str "Lua",Space,Str "Filter",Space,Str "Test:"]
,Para [Str "{{pagebreak}}"]]

With the filter I'd expect the last Para to turn into a RawBlock but...

$ echo -e "Raw Block in md: \n\n\`\`\`{=openxml}\n<w:p>\n\`\`\` \n\nLua Filter Test: \n\n{{pagebreak}}" | pandoc -f markdown -t native --lua-filter="./macro-expander.lua"

Error running filter ./src/servicio-gestion-software/macro-expander.lua:
Could not read list: Could not get Block value: Expected a string but got a nil

Any help would be appreciated.

Thanks!