HA Demo website - switching between demos broken

[SeanPM5]

Checklist

• I have updated to the latest available Home Assistant version.
• I have cleared the cache of my browser.
• I have tried a different browser to see if it is related to my browser.
• I have tried reproducing the issue in safe mode to rule out problems with unsupported custom resources.

Describe the issue you are experiencing

When switching configs in demo site ("next demo" button), it fails to work and throws error prompt which you can see below.

I've not checked demo in a while so not sure how long it's been broken for. Might have to do with new dashboard additions like section visibility etc in 2024.6

HA-Demo-Switch-Configs-SR2.mov

Describe the behavior you expected

able to switch demos

Steps to reproduce the issue

1. Visit https://demo.home-assistant.io/
2. Click "Next demo"
3. See error

What version of Home Assistant Core has the issue?

2024.6 beta

What was the last working version of Home Assistant Core?

No response

In which browser are you experiencing the issue with?

No response

Which operating system are you using to run this browser?

No response

State of relevant entities

No response

Problem-relevant frontend configuration

No response

Javascript errors shown in your browser console/inspector

No response

Additional information

No response

[anscg]

I remember checking Demo on Monday and switching works fine, just noticed the issue also.

[silamon]

It's since the introduction of #20840, pretty recently.

The demo is doing some patching, that is no longer working:
https://github.com/home-assistant/frontend/blob/dev/demo/src/stubs/lovelace.ts#L22-L34