fixes mouse stored inside holder when killed (#92232)

## About The Pull Request

Makes mice go where they were when you kill them, rather than being
stored inside whatever mob was holding them. Mice on your shoulder fall
off, instead.
Also fixes unrelated runtime happening in parallel

## Why It's Good For The Game

fixes  #91057

## Changelog
🆑

fix: mice stored on your person will no longer disappear when killed
/🆑

---------

Co-authored-by: ArcaneMusic <41715314+ArcaneMusic@users.noreply.github.com>

code/modules/mob/living/basic/vermin/mouse.dm

@@ -142,9 +142,19 @@
 	if(!gibbed)
 		var/make_a_corpse = TRUE
 		var/place_to_make_corpse = loc
+		var/must_equip = FALSE
+		var/equip_slot
+		var/mob/holding_mob
+		var/obj/item/mob_holder/found_holder
 		if(istype(loc, /obj/item/mob_holder))//If our mouse is dying in place holder we want to put the dead mouse where the place holder was
-			var/obj/item/mob_holder/found_holder = loc
+			found_holder = loc
 			place_to_make_corpse = found_holder.loc
+			if(istype(found_holder.loc,/mob/living/carbon))
+				holding_mob = found_holder.loc
+				place_to_make_corpse = get_turf(holding_mob)
+				equip_slot = holding_mob.get_slot_by_item(found_holder)
+				if(equip_slot == ITEM_SLOT_HANDS || equip_slot == ITEM_SLOT_RPOCKET || equip_slot == ITEM_SLOT_LPOCKET)
+					must_equip = TRUE
 			if(istype(found_holder.loc, /obj/machinery/microwave))//Microwaves gib things that die when cooked, so we don't need to make a dead body too
 				make_a_corpse = FALSE
 		if(make_a_corpse)
@@ -153,6 +163,11 @@
 			if(HAS_TRAIT(src, TRAIT_BEING_SHOCKED))
 				mouse.desc = "They're toast."
 				mouse.add_atom_colour("#3A3A3A", FIXED_COLOUR_PRIORITY)
+			found_holder?.release(FALSE)
+			if(must_equip)
+				if(equip_slot == ITEM_SLOT_HANDS)
+					holding_mob.dropItemToGround(found_holder)
+				holding_mob.equip_to_slot(mouse,equip_slot)
 	qdel(src)
 
 /mob/living/basic/mouse/UnarmedAttack(atom/attack_target, proximity_flag, list/modifiers)