fix: incorrect discount amount set when item is replaced (#28556)

diff --git a/erpnext/stock/get_item_details.py b/erpnext/stock/get_item_details.py
index e00382b..cd180a4 100644
--- a/erpnext/stock/get_item_details.py
+++ b/erpnext/stock/get_item_details.py
@@ -299,7 +299,7 @@
 		"warehouse": warehouse,
 		"income_account": get_default_income_account(args, item_defaults, item_group_defaults, brand_defaults),
 		"expense_account": expense_account or get_default_expense_account(args, item_defaults, item_group_defaults, brand_defaults) ,
-		"discount_account": None or get_default_discount_account(args, item_defaults),
+		"discount_account": get_default_discount_account(args, item_defaults),
 		"cost_center": get_default_cost_center(args, item_defaults, item_group_defaults, brand_defaults),
 		'has_serial_no': item.has_serial_no,
 		'has_batch_no': item.has_batch_no,
@@ -317,6 +317,7 @@
 		"net_rate": 0.0,
 		"net_amount": 0.0,
 		"discount_percentage": 0.0,
+		"discount_amount": 0.0,
 		"supplier": get_default_supplier(args, item_defaults, item_group_defaults, brand_defaults),
 		"update_stock": args.get("update_stock") if args.get('doctype') in ['Sales Invoice', 'Purchase Invoice'] else 0,
 		"delivered_by_supplier": item.delivered_by_supplier if args.get("doctype") in ["Sales Order", "Sales Invoice"] else 0,