makes vacuums "cold", sort of (#31542)

code/modules/atmospherics/gasmixtures/gas_mixture.dm

@@ -71,6 +71,9 @@ GLOBAL_LIST_INIT(gaslist_cache, init_gaslist_cache())
 	for(var/id in cached_gases)
 		var/gas_data = cached_gases[id]
 		. += gas_data[MOLES] * gas_data[GAS_META][META_GAS_SPECIFIC_HEAT]
+	if(!.) //if no heat capacity, we're a vacuum - things get weird like this but this hack sorta works
+		. += HEAT_CAPACITY_VACUUM
+
 
 /datum/gas_mixture/proc/heat_capacity_archived() //joules per kelvin
 	var/list/cached_gases = gases

code/modules/atmospherics/gasmixtures/immutable_mixtures.dm

@@ -54,7 +54,7 @@
 	initial_temperature = TCMB
 
 /datum/gas_mixture/immutable/space/heat_capacity()
-	return 7000
+	return HEAT_CAPACITY_VACUUM
 
 /datum/gas_mixture/immutable/space/remove()
 	return copy() //we're always empty, so we can just return a copy.