Sound tab crashes on Mac Safari + bluetooth headphones + google hangouts

[ericrosenbaum]

On Mac Safari, we're seeing a crash if you're using bluetooth headphones, you have a google hangout running that is accessing your microphone, and you switch to the sounds tab.

To repro:

1. turn on bluetooth headphones

• On Mac Chrome:

2. Start or enter a google hangout with microphone enabled. The preview screen (before you have joined the hangout) works- it accesses your microphone and shows a little green audio indicator in the bottom left.

• On mac Safari:

3. reload Scratch site and create a new project
4. click on the Sounds tab
5. you will see BSOD

We're seeing a console error containing:
Unhandled Error: createBuffer@[native code]
and
[Error] NotSupportedError: The operation is not supported. createBuffer

Operating System and Browser

Mac OS 10.15.2 Safari 13.0.4
also: Mac OS 10.14.5 Safari 12.1.1

[apple502j]

Similar issue: #2216