hackmdio/hackmd

I'm trying to configure an instance of codimd at heroku to use oauth2 against my own provider. I'm not allowing anonymous edits. I've got it to the point that login is successful, but when I create a new note, I get a crash:

2020-06-15T14:58:08.632614+00:00 heroku[router]: at=info method=GET path="/sipcore" host=... request_id=2435563d-38f0-4441-9e40-07047c5d9a61 fwd="..." dyno=web.1 connect=0ms service=57ms status=500 bytes=678 protocol=https
2020-06-15T14:58:08.612464+00:00 app[web.1]: 2020-06-15T14:58:08.612Z info:     deserializeUser: 71f5dbfd-04a0-4fd4-b688-9ab8e1a4fd19
2020-06-15T14:58:08.622978+00:00 app[web.1]: Error: can not create note
2020-06-15T14:58:08.622979+00:00 app[web.1]:     at createNote (/app/lib/note/index.js:38:11)
2020-06-15T14:58:08.622980+00:00 app[web.1]:     at showNote (/app/lib/note/index.js:65:18)

This corresponds to the code in note/index.js:

async function createNote (userId, noteAlias) {
  if (!config.allowAnonymous && !userId) {
    throw new Error('can not create note')
  }

So, why after a successful login, is userId not set? What else do I need to change in the config?

If there's a better place to ask this, please let me know.