FYI,

This bug does not occur on the 64-bit version of the game only the 32-bit.  The
32-bit is very unstable for me also, it crashes quite often.

Unfortunately, the 64-bit version's in-game audio is broken on Proton
currently.

I have spent hours testing different settings on and off for over a year, never
managed to find a setting that cured the issue.  The game works fine on
proprietary drivers.

System info:
-- Arch 64-bit
-- GPU: RX Vega 56
-- Mesa 18.3.0-devel (git-e345247092)
-- Kernel 4.18.5