Can't edit post title, javascript errors

Bug
1

I see the :pencil: icon, and can modify the text, but there is no save button.

I have the default theme, with (an old version of) DiscoTOC - but I don’t think that’s the problem (is it?).

I’ve tried this, to no avail:

./launcher enter app
rails c
Discourse.clear_all_theme_cache!

and the console says:

Uncaught (in promise) TypeError: Cannot read properties of null (reading 'syscall')
    at Object.evaluate (index.js:103:17)
    at tr.evaluateSyscall (index.js:2873:20)
    at tr.evaluateInner (index.js:2852:64)
    at tr.evaluateOuter (index.js:2849:10)
    at tH.next (index.js:4167:45)
    at tH._execute (index.js:4157:21)
    at tH.execute (index.js:4133:41)
    at tj.handleException (index.js:3450:19)
    at tR.handleException (index.js:3592:52)
    at tF.throw (index.js:3414:16)
    at G.evaluate (index.js:565:42)
    at tF._execute (index.js:3401:34)
    at tF.execute (index.js:3393:17)
    at tU.rerender (index.js:3610:8)
    at tq.render (index-BCp6wOJU.js:4639:55)
    at index-BCp6wOJU.js:4934:16
    at eX (index.js:2414:7)
    at tG._renderRoots (index-BCp6wOJU.js:4914:7)
    at tG._renderRootsTransaction (index-BCp6wOJU.js:4962:12)
    at tG._revalidate (index-BCp6wOJU.js:4995:10)
    at invoke (index.js:262:14)
    at m.flush (index.js:180:11)
    at g.flush (index.js:334:19)
    at q._end (index.js:762:32)
    at _boundAutorunEnd (index.js:499:12)

I have user reports of other similar UI bugs since last update (to 3.6.0.beta1-dev), but this is the one I can also reproduce myself. Reproduced in Brave and Chrome.