Fix stock-out boot, transfer 500, Clear buttons and uncaught engine errors

Return JSON from any uncaught engine exception, stop the empty stock-out warehouse list aborting page boot, reject non-transfer rows in the transfer lookup, define the missing reset_input helper, and remove a stale unreferenced copy of confirm_order.php.

app/assets/js/custom.js

@@ -1074,6 +1074,36 @@ function to_iso_date(dateStr) {
 }
 
 
+/**
+ * Clear every field inside a form or form-like container — the "Clear" buttons
+ * on the master-data pages. It was called by five pages but never defined, so
+ * each click threw a ReferenceError, and where the container is a <div> rather
+ * than a <form> (Chart of Accounts, Departments) the button did nothing at all.
+ * Disabled and hidden inputs are left alone: those carry the record id and
+ * locked values, not user input.
+ */
+function reset_input(selector) {
+  var $scope = $(selector);
+  if (!$scope.length) return;
+
+  $scope.find('input, textarea, select').each(function () {
+    if (this.disabled || this.type === 'hidden' || this.type === 'button' || this.type === 'submit') return;
+
+    if (this._flatpickr) {
+      this._flatpickr.clear();
+    } else if (this.type === 'checkbox' || this.type === 'radio') {
+      this.checked = this.defaultChecked;
+    } else if (this.tagName === 'SELECT') {
+      this.selectedIndex = 0;
+    } else {
+      this.value = '';
+    }
+
+    $(this).removeAttr('secondary').removeClass('is-invalid is-valid');
+  });
+}
+
+
 function round_dp(value, places) {
   var factor = Math.pow(10, places);
   return Math.round((Number(value) + Number.EPSILON) * factor) / factor;