The record type [] is invalid

I am trying to use from code on a prior project to set a date last ordered on item records. It runs on POs and looks at each item to reset the Last Ordered Date (a custom field).

I am struggling to get it to recognize when I have a serial number that it uses serializedinventoryitem instead of inventoryitem. I feel like I am probably missing something missing obvious. Here is the code:


function updateLastReceivedDate()
{
var item;
var lastPurchaseDate ;
var trandate="";
var itemType;
var item_rec_type ="";
var itemCount = nlapiGetLineItemCount("item");
var purchaseMonth;
var purchaseYear;
var purchaseDay;

for(var i = 1; i<= itemCount; i++){