Steps to reproduce:

1) Download attached project and open in Unity
2) Open Scene "Sample Scene"
3) Press Play
4) Click on "Record Internal" or "RecordBT" button
Observe the crash
Note: if the Editor didn't crash, repeat steps 3 and 4

Expected result: No crash

Reproduced with:
2018.3.0a6, 2018.3.0a10, 2018.3.0a11

Not reproduced with:
2018.2.4f1

Regression in:
2018.3.0a1 - 2018.3.0a5 (I couldn't check in those versions because of the PackageManager errors)

Reproduced using Windows 10 machine and Android devices

Note: There was no microphone connected to the devices
---------------------------------------------------------
Fixed in:2018.3.0b1