Minor UX upgrade: Landed cost voucher should show some error on entering purchase invoice without update stock

So I know LCV does not show PI in the autocomplete list if it does not have “Update Stock” ticked. One of the employees thought this was some sort of bug and just copied the ID number of the PI into LCV and it worked. On submitting it, the PI updated the stock. a purchase receipt was also created which updated the stock twice. I think this can lead to some disastrous results and can be avoided by some simple validation and an error message.