Porting update_icon improvements. Part 1.

code/game/objects/items/implants/implantcase.dm

@@ -10,18 +10,14 @@
 	throw_range = 5
 	w_class = WEIGHT_CLASS_TINY
 	custom_materials = list(/datum/material/glass=500)
-	var/obj/item/implant/imp = null
+	var/obj/item/implant/imp
 	var/imp_type
 
-
-/obj/item/implantcase/update_icon()
+/obj/item/implantcase/update_icon_state()
 	if(imp)
 		icon_state = "implantcase-[imp.item_color]"
-		reagents = imp.reagents
 	else
 		icon_state = "implantcase-0"
-		reagents = null
-
 
 /obj/item/implantcase/attackby(obj/item/W, mob/user, params)
 	if(istype(W, /obj/item/pen))
@@ -46,6 +42,7 @@
 			imp = I.imp
 			I.imp = null
 			update_icon()
+			reagents = imp.reagents
 			I.update_icon()
 		else
 			if(imp)
@@ -54,6 +51,7 @@
 				imp.forceMove(I)
 				I.imp = imp
 				imp = null
+				reagents = null
 				update_icon()
 			I.update_icon()