Fixes debug spam on simplemob hands

2 unique cases of simplemob hands causimg debug spam just because they are not in line with regular hands,

as in they do not properly reference hud, this ned proc for add overlays handles these runtimes.

code/_onclick/hud/screen_objects_zz_ch.dm

@@ -0,0 +1,30 @@
+//Invesitgating a runtime made me discover that all simplemobs have HUD on hands set to themselves
+//Which cause this original code to die because the mob does not have a mymob var...
+//So yeah this is why we now check if it is type of mob first...
+//Is this pretty? Fuck no, but its how i know to fix it -shark
+//Oh also the swap button on simple mob hands has hud set to null so we also need to catch that.
+/obj/screen/inventory/add_overlays()
+	if(!hud) //Simplemob swap hands button has this set to null :)
+		return
+	var/mob/user
+	if(istype(hud,/mob )) //Simplemob hands directly reference the mob in hud, dont ask me.
+		user = hud
+	else
+		user = hud.mymob //original intended behaviour
+	if(hud && user && slot_id)
+
+		var/obj/item/holding = user.get_active_hand()
+
+		if(!holding || user.get_equipped_item(slot_id))
+			return
+
+		var/image/item_overlay = image(holding)
+		item_overlay.alpha = 92
+
+		if(!holding.mob_can_equip(user, slot_id, disable_warning = TRUE))
+			item_overlay.color = "#ff0000"
+		else
+			item_overlay.color = "#00ff00"
+
+		object_overlays += item_overlay
+		add_overlay(object_overlays)