fix: check item_code in all rows of po_items (backport #31741) (#31842)

fix: check item_code in all rows of po_items (#31741)

fix: check the item code in each row of PO items
(cherry picked from commit 0047e18)

Co-authored-by: Sagar Sharma <sagarsharma.s312@gmail.com>

erpnext/manufacturing/doctype/production_plan/production_plan.py

@@ -639,6 +639,9 @@ def get_sub_assembly_items(self, manufacturing_type=None):
 		sub_assembly_items_store = []  # temporary store to process all subassembly items
 
 		for row in self.po_items:
+			if not row.item_code:
+				frappe.throw(_("Row #{0}: Please select Item Code in Assembly Items").format(row.idx))
+
 			bom_data = []
 			get_sub_assembly_items(row.bom_no, bom_data, row.planned_qty)
 			self.set_sub_assembly_items_based_on_level(row, bom_data, manufacturing_type)