That's interesting! It works for me, both on Firefox and Chromium. May I ask wha...

dygd · on April 6, 2021

Firefox 87.0 (64-bit) on Win10. It is reproducible. Disabling uBlock Origin didn't make a difference. Let me know if I can help debug!

kouteiheika · on April 6, 2021

Okay, so this is indeed very interesting. I just launched the same version of Firefox in a Win10 VM, and it works there too. So it might be one of your extensions, maybe? (I use uBlock Origin too, so that's not it.)

Could you try these things out please?

1. Try disabling all of your extensions and try again. (IIRC by default private mode disables all of the extensions, so that should be an easy way to do it.)

2. Can you open the dev console and try running something like this in it?

    document.querySelector("audio").play()

Based on your original error either the `previousElementSibling` is not an `<audio>` tag, or for some reason audio tags don't have a play method, so it'd be good to know which one it is.

dygd · on April 7, 2021

Hello, just tried disabling extensions one by one and it seems that https://addons.mozilla.org/en-GB/firefox/addon/rikaichamp/ causes the problem. I can reliably enable/disable the extension to reproduce/fix the problem.