In which case this code snippet may throw error "Attempt to index nil with :IsA()?"

[GamEditoPro]

I have wrote this code as part of a more complex system. But I genuinely can’t understand in which case New.Parent will be nil?

Data[Player].Connections.CharacterChildAdded = Character.DescendantAdded:Connect(function(New)
	if New.Parent:IsA("Accessory") and New:IsA("BasePart") then
		New.CanCollide = false
		New.CanQuery = false
		New.CanTouch = false
	end
end)

[iATtaCk_Noobsi (Noob)]

New.Parent will be nil if you’ve set the Parent to nil (you probably didn’t) or if New was destroyed. You’ve likely destroyed the New thing somewhere in a different script

EDIT taking another look I’m probably wrong about this..

[GamEditoPro]

After hours of debugging, I have found that it was caused by TouchInterest instance. Weird. I can’t even see it.

[2112Jay]

The only time this error occurs in this context is if Parent is nil at the moment DescendantAdded fires.

Wonder if this would catch both instances.. (it should)

Data[Player].Connections.CharacterChildAdded = Character.DescendantAdded:Connect(function(New)
    local parent = New.Parent or New.AncestryChanged:Wait()
    if New:IsA("BasePart") and parent:IsA("Accessory") then
        New.CanCollide = false
        New.CanQuery = false
        New.CanTouch = false
    end
end)