Added config entry to toggle lavaland (#17705)

* Added config entry to toggle lavaland

* addressed review

* Do not go gentle into that good night

* Actually this is the way to do it

code/modules/shuttle/navigation_computer.dm

@@ -27,7 +27,7 @@
 	GLOB.navigation_computers += src
 	if(access_station)
 		jumpto_ports += list("nav_z[level_name_to_num(MAIN_STATION)]" = 1)
-	if(access_mining)
+	if(access_mining && GLOB.configuration.ruins.enable_lavaland)
 		jumpto_ports += list("nav_z[level_name_to_num(MINING)]" = 1)
 
 /obj/machinery/computer/camera_advanced/shuttle_docker/Destroy()

code/modules/space_management/level_traits.dm

@@ -61,6 +61,8 @@ GLOBAL_LIST_INIT(default_map_traits, list(CC_TRANSITION_CONFIG))
 
 /proc/level_name_to_num(name)
 	var/datum/space_level/S = GLOB.space_manager.get_zlev_by_name(name)
+	if(!S)
+		CRASH("Unknown z-level name: [name]")
 	return S.zpos
 
 /**