Fixes some stuff with legion infections (#3450)

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## About The Pull Request

homeless skulls no longer complain about not being fed

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## Changelog

:cl:
fix: legion skulls will no longer check if they should rise up and
consume their owner if they are ownerless
/:cl:

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Signed-off-by: Theos <[email protected]>

code/modules/mob/living/simple_animal/hostile/mining_mobs/hivelord.dm

@@ -297,6 +297,8 @@
 
 /// track our timers and reagents
 /obj/item/organ/legion_skull/proc/skull_check()
+	if(!owner)
+		return
 	if(!malignance)
 		malignance = new()
 		malignance.infect(owner, FALSE)