Fixed an evidence bag runtime error and added a few CRASH() checks to /obj/machinery/disposal

code/defines/obj.dm

@@ -264,7 +264,7 @@
 	var/burning = null
 	var/hitsound = null
 	var/w_class = 3.0
-	var/wielded = 0
+	var/wielded = 0 // 1 if item is two handed and grabbed with two hands
 	var/twohanded = 0 // Two handed and wielded off by default, nyoro~n -Agouri
 	var/force_unwielded = 0
 	var/force_wielded = 0

code/game/objects/items/weapons/evidence.dm

@@ -33,11 +33,14 @@
 	desc = "An evidence bag containing \a [O]. [O.desc]"
 
 /obj/item/weapon/evidencebag/attack_self(mob/user as mob)
-	var/obj/item/I = src.contents[1]
-	user << "You take the [I] out of the [src]."
-	I.loc = user.loc
-	src.underlays -= I
-	icon_state = "evidenceobj"
+	if (src.contents.len > 0)
+		var/obj/item/I = src.contents[1]
+		user << "You take the [I] out of the [src]."
+		I.loc = user.loc
+		src.underlays -= I
+		icon_state = "evidenceobj"
+	else
+		user << "The [src] is empty."
 
 /obj/item/weapon/storage/box/evidence
 	name = "evidence bag box"

code/modules/recycling/disposal.dm

@@ -73,9 +73,17 @@
 		if(isrobot(user))
 			return
 
-		else if (!isnull(I)) // As per code/game/atom_procs.dm, this shouldn't even be required, but for some reason is. -- Abi79
+		else
+			if(isnull(I)) // Added these calls to CRASH to diagnose a runtime error that may be one of the causes of erasure errors --Abi79
+				CRASH("disposal/attackby() was called, but I was nulled before calling user.drop_item()")
+
+			var/debug_item_name = I.name
+
 			user.drop_item()
 
+			if(isnull(I))
+				CRASH("disposal/attackby() was called with [debug_item_name] as I, but I was nulled after calling user.drop_item()")
+
 			I.loc = src
 			user << "You place \the [I] into the [src]."
 			for(var/mob/M in viewers(src))