Fixes #9453 and fixes #10614

code/game/objects/items/stacks/stack.dm

@@ -184,11 +184,9 @@
 	if(!uses_charge)
 		amount -= used
 		if (amount <= 0)
-			spawn(0) //delete the empty stack once the current context yields
-				if (amount <= 0) //check again in case someone transferred stuff to us
-					if(usr)
-						usr.remove_from_mob(src)
-					qdel(src)
+			if(usr)
+				usr.remove_from_mob(src)
+			qdel(src) //should be safe to qdel immediately since if someone is still using this stack it will persist for a little while longer
 		return 1
 	else
 		if(get_amount() < used)

code/modules/mob/living/silicon/robot/drone/drone_items.dm

@@ -87,6 +87,9 @@
 
 /obj/item/weapon/gripper/no_use //Used when you want to hold and put items in other things, but not able to 'use' the item
 
+/obj/item/weapon/gripper/no_use/attack_self(mob/user as mob)
+	return
+
 /obj/item/weapon/gripper/no_use/loader //This is used to disallow building with metal.
 	name = "sheet loader"
 	desc = "A specialized loading device, designed to pick up and insert sheets of materials inside machines."
@@ -101,9 +104,6 @@
 		return wrapped.attack_self(user)
 	return ..()
 
-/obj/item/weapon/gripper/no_use/attack_self(mob/user as mob)
-	return
-
 /obj/item/weapon/gripper/verb/drop_item()
 
 	set name = "Drop Item"
@@ -130,6 +130,8 @@
 		force_holder = wrapped.force
 		wrapped.force = 0.0
 		wrapped.attack(M,user)
+		if(deleted(wrapped))
+			wrapped = null
 		return 1
 	return 0
 

code/modules/reagents/Chemistry-Machinery.dm

@@ -733,17 +733,13 @@
 
 	if (usr.stat != 0)
 		return
-	if (holdingitems && holdingitems.len == 0)
+	if (!holdingitems || holdingitems.len == 0)
 		return
 
 	for(var/obj/item/O in holdingitems)
 		O.loc = src.loc
 		holdingitems -= O
-	holdingitems = list()
-
-/obj/machinery/reagentgrinder/proc/remove_object(var/obj/item/O)
-	holdingitems -= O
-	qdel(O)
+	holdingitems.Cut()
 
 /obj/machinery/reagentgrinder/proc/grind()
 
@@ -766,10 +762,6 @@
 	// Process.
 	for (var/obj/item/O in holdingitems)
 
-		if(!O || !istype(O))
-			holdingitems -= null
-			continue
-
 		var/remaining_volume = beaker.reagents.maximum_volume - beaker.reagents.total_volume
 		if(remaining_volume <= 0)
 			break
@@ -780,13 +772,16 @@
 				var/amount_to_take = max(0,min(stack.amount,round(remaining_volume/REAGENTS_PER_SHEET)))
 				if(amount_to_take)
 					stack.use(amount_to_take)
+					if(deleted(stack))
+						holdingitems -= stack
 					beaker.reagents.add_reagent(sheet_reagents[stack.type], (amount_to_take*REAGENTS_PER_SHEET))
 					continue
 
 		if(O.reagents)
 			O.reagents.trans_to(beaker, min(O.reagents.total_volume, remaining_volume))
 			if(O.reagents.total_volume == 0)
-				remove_object(O)
+				holdingitems -= O
+				qdel(O)
 			if (beaker.reagents.total_volume >= beaker.reagents.maximum_volume)
 				break