fix: supplier removed on selection of item (backport #38712) (#38713)

fix: supplier removed on selection of item (#38712)

(cherry picked from commit db24e24)

Co-authored-by: rohitwaghchaure <rohitw1991@gmail.com>
(cherry picked from commit feb452b)

erpnext/stock/get_item_details.py

@@ -357,7 +357,6 @@ def get_basic_details(args, item, overwrite_warehouse=True):
 			"net_amount": 0.0,
 			"discount_percentage": 0.0,
 			"discount_amount": flt(args.discount_amount) or 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,
@@ -377,6 +376,10 @@ def get_basic_details(args, item, overwrite_warehouse=True):
 		}
 	)
 
+	default_supplier = get_default_supplier(args, item_defaults, item_group_defaults, brand_defaults)
+	if default_supplier:
+		out.supplier = default_supplier
+
 	if item.get("enable_deferred_revenue") or item.get("enable_deferred_expense"):
 		out.update(calculate_service_end_date(args, item))