Fixed some major incompetency from 2018.

// If someone will place 0 of some gas there, SHIT WILL BREAK. Do not do that.
LINDA_turf_tile.dm, line 16.

code/game/turfs/simulated/floor/plating/asteroid.dm

@@ -442,7 +442,7 @@
 	name = "icy snow"
 	desc = "Looks colder."
 	baseturfs = /turf/open/floor/plating/asteroid/snow/ice
-	initial_gas_mix = "o2=0;n2=82;plasma=24;TEMP=120"
+	initial_gas_mix = "n2=82;plasma=24;TEMP=120"
 	floor_variance = 0
 	icon_state = "snow-ice"
 	icon_plating = "snow-ice"

code/game/turfs/simulated/floor/plating/misc_plating.dm

@@ -230,7 +230,7 @@
 	heavyfootstep = FOOTSTEP_GENERIC_HEAVY
 
 /turf/open/floor/plating/snowed/cavern
-	initial_gas_mix = "o2=0;n2=82;plasma=24;TEMP=120"
+	initial_gas_mix = "n2=82;plasma=24;TEMP=120"
 
 /turf/open/floor/plating/snowed/smoothed
 	smooth = SMOOTH_MORE | SMOOTH_BORDER