changes Assimilate_Air() behavior when there are no atmos_adjacent_turfs

code/game/turfs/turf.dm

@@ -277,12 +277,12 @@
 
 //////Assimilate Air//////
 /turf/open/proc/Assimilate_Air()
-	if(blocks_air)
+	var/turf_count = LAZYLEN(atmos_adjacent_turfs)
+	if(blocks_air || !turf_count) //if there weren't any open turfs, no need to update.
 		return
 
 	var/datum/gas_mixture/total = new//Holders to assimilate air from nearby turfs
 	var/list/total_gases = total.gases
-	var/turf_count = LAZYLEN(atmos_adjacent_turfs)
 
 	for(var/T in atmos_adjacent_turfs)
 		var/turf/open/S = T
@@ -296,9 +296,6 @@
 
 	air.copy_from(total)
 
-	if(!turf_count) //if there weren't any open turfs, no need to update.
-		return
-
 	var/list/air_gases = air.gases
 	for(var/id in air_gases)
 		air_gases[id][MOLES] /= turf_count //Averages contents of the turfs, ignoring walls and the like