refactor: disallow '0' qty return invoices with stock effect

erpnext/controllers/accounts_controller.py

@@ -169,6 +169,13 @@ class AccountsController(TransactionBase):
 		if not self.get("is_return") and not self.get("is_debit_note"):
 			self.validate_qty_is_not_zero()
 
+		if (
+			self.doctype in ["Sales Invoice", "Purchase Invoice"]
+			and self.get("is_return")
+			and self.get("update_stock")
+		):
+			self.validate_zero_qty_for_return_invoices_with_stock()
+
 		if self.get("_action") and self._action != "update_after_submit":
 			self.set_missing_values(for_validate=True)
 
@@ -1045,6 +1052,18 @@ class AccountsController(TransactionBase):
 		else:
 			return flt(args.get(field, 0) / self.get("conversion_rate", 1))
 
+	def validate_zero_qty_for_return_invoices_with_stock(self):
+		rows = []
+		for item in self.items:
+			if not flt(item.qty):
+				rows.append(item)
+		if rows:
+			frappe.throw(
+				_(
+					"For Return Invoices with Stock effect, '0' qty Items are not allowed. Following rows are affected: {0}"
+				).format(frappe.bold(comma_and(["#" + str(x.idx) for x in rows])))
+			)
+
 	def validate_qty_is_not_zero(self):
 		for item in self.items:
 			if self.doctype == "Purchase Receipt" and item.rejected_qty: