Logging Fix: In the GameState element, set "headset" to null if in desktop mode

[LswaN58]

We can save ourselves potential logic bugs in data processing (and characters in logging) by setting the "headset" element in the GameState column to null for all events when the app is in "desktop" mode.
In desktop mode, "headset" isn't a meaningful concept, so it's more logically meaningful to simply set that element to null.