Adding Headers on markdown causes error

[thehamstermuffin]

Adding any header on markdown causes an error and can't build.

---
title: Before what this whose
date: "2024-07-23"
categories: [Accessibility,]
---
## header     <-------------------------------------
content content content

With this error message (edited personal stuff)

ERROR Rebuild failed: render: [en v1.0.0 guest] failed to render pages: render of "content/notes/mynote.md" failed: "/home/user/.cache/hugo_cache/modules/filecache/modules/pkg/mod/github.com/michenriksen/hugo-theme-til@v0.6.0/layouts/_default/single.html:36:7": execute of template failed at <partial "page/meta" .>: error calling partial: "/home/user/.cache/hugo_cache/modules/filecache/modules/pkg/mod/github.com/michenriksen/hugo-theme-til@v0.6.0/layouts/partials/page/meta.html:1:13": execute of template failed at <partialCached "functions/linkable-pages" .>: error calling partialCached: "/home/user/.cache/hugo_cache/modules/filecache/modules/pkg/mod/github.com/michenriksen/hugo-theme-til@v0.6.0/layouts/partials/functions/linkable-pages.html:4:15": execute of template failed at <.Content>: error calling Content: "content/notes/note-with-header.md:3:10": "/home/user/.cache/hugo_cache/modules/filecache/modules/pkg/mod/github.com/michenriksen/hugo-theme-til@v0.6.0/layouts/_default/_markup/render-heading.html:3:10": execute of template failed at <partial "svg/Link.html">: "/home/user/.cache/hugo_cache/modules/filecache/modules/pkg/mod/github.com/michenriksen/hugo-theme-til@v0.6.0/layouts/partials/svg/Link.html:10:31": execute of template failed at <.class>: can’t evaluate field class in type string

the error seems to come from layouts/_default/_markup/render-heading.html