more harddels please! (shiptest-ss13#3640)

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## About The Pull Request
Cleans up 3 potentially harddel causing references, specifically
-particle_holders deployed when a mob is bleeding or obj is burning
-snake in my boot

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## Why It's Good For The Game
WAITER WAITER
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## Changelog

:cl:
fix: cleans up 3 potentially sticky refs
/:cl:

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---------

Signed-off-by: Sun-Soaked <[email protected]>
Co-authored-by: Mark Suckerberg <[email protected]>

code/game/objects/objs.dm

@@ -84,7 +84,9 @@
 	if(!ismachinery(src))
 		STOP_PROCESSING(SSobj, src) // TODO: Have a processing bitflag to reduce on unnecessary loops through the processing lists
 	SStgui.close_uis(src)
-	. = ..()
+	if(burning_particles)
+		QDEL_NULL(burning_particles)
+	return ..()
 
 
 /obj/throw_at(atom/target, range, speed, mob/thrower, spin=1, diagonals_first = 0, datum/callback/callback, force, gentle = FALSE, quickstart = TRUE)

code/modules/clothing/shoes/miscellaneous.dm

@@ -217,6 +217,9 @@
 		var/mob/living/simple_animal/hostile/retaliate/poison/snake/bootsnake = new/mob/living/simple_animal/hostile/retaliate/poison/snake(src)
 		occupants += bootsnake
 
+/obj/item/clothing/shoes/cowboy/Destroy()
+	QDEL_LIST(occupants)
+	return ..()
 
 /obj/item/clothing/shoes/cowboy/equipped(mob/living/carbon/user, slot)
 	. = ..()

code/modules/mob/living/carbon/human/human.dm

@@ -42,6 +42,8 @@
 	QDEL_NULL(physiology)
 	QDEL_LIST(bioware)
 	GLOB.human_list -= src
+	if(blood_particle)
+		QDEL_NULL(blood_particle)
 	return ..()