Minor refactor of how gas IDs are handled

code/modules/mob/living/life.dm

@@ -92,7 +92,7 @@
 		ExtinguishMob()
 		return
 	var/datum/gas_mixture/G = loc.return_air() // Check if we're standing in an oxygenless environment
-	if(!G.gases["o2"] || G.gases["o2"][MOLES] < 1)
+	if(!G.gases[/datum/gas/oxygen] || G.gases[/datum/gas/oxygen][MOLES] < 1)
 		ExtinguishMob() //If there's no oxygen in the tile we're on, put out the fire
 		return
 	var/turf/location = get_turf(src)
@@ -123,5 +123,3 @@
 
 /mob/living/proc/update_damage_hud()
 	return
-
-