Arcade sounds persist on home screen if click away while sim is loading

[thsparks]

If you have a song in your arcade game and happen to click back to the home page while the sim is loading, the sounds will still play on the home page.

For example, open https://arcade.makecode.com/S77938-92177-54945-21542, edit code, and then, while the sim is still loading, click the MakeCode Arcade text in the header bar to go home. Then wait a moment and you'll hear the sound start up.

This is not a regression. Also repros in live.