Unofficial Fallout 4 Patch

Posting the full script here because this error is somewhat unexpected:

Scriptname DLC06: PipboyMiscItemScript extends ObjectReference Const

Faction property WorkshopNPCFaction auto const mandatory 

Armor property DLC06PipboyVault88 auto const mandatory 

Event OnContainerChanged(ObjectReference akNewContainer, ObjectReference akOldContainer)
    if akNewContainer is Actor
    	Actor myActor = akNewContainer as Actor
    	if myActor != Game.GetPlayer() && myActor.IsInFaction(WorkshopNPCFaction) && myActor.GetItemCount(DLC06PipboyVault88) == 0
    		debug.trace(self + " OnContainerChanged: equipping pipboy on " + myActor)
    		; add and equip real pipboy on actor
    		myActor.EquipItem(DLC06PipboyVault88)
    		myActor.RemoveItem(self.GetBaseObject())
    	endif
    endif
EndEvent

The script equips a PipBoy on an actor. It runs on the MiscItem PipBoy objects in vault 88's PipBoy crate. These items cannot be equipped on actors (only armor items can), so the script silently replaces the MiscItem PipBoy with an Armor PipBoy and equips that one instead. The MiscItem PipBoy is subsequently removed. This means that the script always runs twice if you give a PipBoy to a settler: the event fires again when the PipBoy is removed from the settler's inventory.

In the event that fires upon removal of the item, akNewContainer = none, and this is where the error occurs:

if akNewContainer is Actor

The "is" check is supposed to return true if akNewContainer is an actor. Though, it is NOT supposed to only return true if the actor is not none. In fact, it still returns true if the actor IS none because none is a perfectly valid value for an actor

To make this work as expected, an "as" check has to be used. Unlike the "is" check, the "as" check casts akNewContainer as an actor (so it is also a tad slower than an "is" check) and then basically performe an "if <actor>" check that will never return true if the actor is none.