Fix item counts, PR/QT conversions, validation and department loss

app/assets/js/custom.js

@@ -581,9 +581,19 @@ function load_formula_options(select_id, document_type, selected_id, onLoaded) {
   });
 }
 
+// Line tax rate; derived from tax_amount / total_price when only the amount was stored
+function line_tax_rate(item) {
+  var rate   = parseFloat(item.tax_rate)    || 0;
+  var amount = parseFloat(item.tax_amount)  || 0;
+  var total  = parseFloat(item.total_price) || 0;
+  if (rate === 0 && amount > 0 && total > 0) rate = round_dp(amount / total * 100, 2);
+  return rate;
+}
+
+// Returns the request promise so callers can await the options before selecting a value
 function load_departments(select_id, selected_id) {
   var ctx = document.getElementById('session-context');
-  ajax_request({
+  return ajax_request({
     url:       server_url + 'accounting/api/engine/department.php',
     action:    'get',
     queueLock: false,