Fails to publish with footnotes

[asr1]

I see that footnotes are listed as a supported feature, but when I try to publish a file containing a footnote (using [^1] syntax), Vercel gives an undefined error on the footnote anchor:

10:37:33.286 | [11ty] Original error stack trace: TypeError: Cannot read properties of undefined (reading 'docId')
10:37:33.286 | [11ty]     at Object.render_footnote_anchor_name [as footnote_anchor_name] (/vercel/path0/node_modules/markdown-it-footnote/index.js:12:18)

Removing the footnote resolves the issue.