Converts Most Destroys to use QDEL_NULL

code/game/objects/items/devices/guitar.dm

@@ -17,8 +17,7 @@
 	song.instrumentExt = "ogg"
 
 /obj/item/device/guitar/Destroy()
-	qdel(song)
-	song = null
+	QDEL_NULL(song)
 	return ..()
 
 /obj/item/device/guitar/attack_self(mob/user as mob)

code/game/objects/items/devices/laserpointer.dm

@@ -35,9 +35,7 @@
 		pointer_icon_state = pick("red_laser","green_laser","blue_laser","purple_laser")
 
 /obj/item/device/laser_pointer/Destroy()
-	if(diode)
-		qdel(diode)
-		diode = null
+	QDEL_NULL(diode)
 	return ..()
 
 /obj/item/device/laser_pointer/upgraded/New()

code/game/objects/items/devices/paicard.dm

@@ -12,7 +12,7 @@
 	var/looking_for_personality = 0
 	var/mob/living/silicon/pai/pai
 	var/list/faction = list("neutral") // The factions the pAI will inherit from the card
-	
+
 /obj/item/device/paicard/syndicate
 	name = "syndicate personal AI device"
 	faction = list("syndicate")
@@ -33,9 +33,7 @@
 		pai.ghostize()
 		qdel(pai)
 		pai = null
-	if(radio)
-		qdel(radio)
-		radio = null
+	QDEL_NULL(radio)
 	return ..()
 
 /obj/item/device/paicard/attack_self(mob/user)

code/game/objects/items/devices/sensor_device.dm

@@ -12,8 +12,7 @@
 	crew_monitor = new(src)
 
 /obj/item/device/sensor_device/Destroy()
-	qdel(crew_monitor)
-	crew_monitor = null
+	QDEL_NULL(crew_monitor)
 	return ..()
 
 /obj/item/device/sensor_device/attack_self(mob/user as mob)

code/game/objects/items/devices/taperecorder.dm

@@ -21,9 +21,7 @@
 	update_icon()
 
 /obj/item/device/taperecorder/Destroy()
-	if(mytape)
-		qdel(mytape)
-		mytape = null
+	QDEL_NULL(mytape)
 	return ..()
 
 /obj/item/device/taperecorder/examine(mob/user)

code/game/objects/items/devices/transfer_valve.dm

@@ -13,15 +13,9 @@
 	origin_tech = "materials=1;engineering=1"
 
 /obj/item/device/transfer_valve/Destroy()
-	if(tank_one)
-		qdel(tank_one)
-		tank_one = null
-	if(tank_two)
-		qdel(tank_two)
-		tank_two = null
-	if(attached_device)
-		qdel(attached_device)
-		attached_device = null
+	QDEL_NULL(tank_one)
+	QDEL_NULL(tank_two)
+	QDEL_NULL(attached_device)
 	attacher = null
 	return ..()
 

code/game/objects/items/devices/violin.dm

@@ -18,8 +18,7 @@
 	song.instrumentExt = "ogg"
 
 /obj/item/device/violin/Destroy()
-	qdel(song)
-	song = null
+	QDEL_NULL(song)
 	return ..()
 
 /obj/item/device/violin/initialize()