Fixes Guardian Spirits not being able to move in stopped time along with their user. (#35895)

* I have no idea if this will work, but hopefully makes stands immune to timestops if their master is.

* That looks better

* Maybe that will work, maybe it will not.

* Checks if the summoner actually exists.

As per review advice from @DaedalusGame.

code/modules/fields/timestop.dm

@@ -29,6 +29,9 @@
 	for(var/mob/living/L in GLOB.player_list)
 		if(locate(/obj/effect/proc_holder/spell/aoe_turf/conjure/timestop) in L.mind.spell_list) //People who can stop time are immune to its effects
 			immune[L] = TRUE
+	for(var/mob/living/simple_animal/hostile/guardian/G in GLOB.parasites)
+		if(G.summoner && locate(/obj/effect/proc_holder/spell/aoe_turf/conjure/timestop) in G.summoner.mind.spell_list) //It would only make sense that a person's stand would also be immune.
+			immune[G] = TRUE
 	if(start)
 		timestop()