Merge pull request #18576 from deepeshgarg007/taxes_and_totals_v12

fix: Error handling in taxes and totals
diff --git a/erpnext/controllers/taxes_and_totals.py b/erpnext/controllers/taxes_and_totals.py
index b774037..d2db9d0 100644
--- a/erpnext/controllers/taxes_and_totals.py
+++ b/erpnext/controllers/taxes_and_totals.py
@@ -82,7 +82,7 @@
 
 				item.net_rate = item.rate
 
-				if not item.qty and self.doc.is_return:
+				if not item.qty and self.doc.get("is_return"):
 					item.amount = flt(-1 * item.rate, item.precision("amount"))
 				else:
 					item.amount = flt(item.rate * item.qty,	item.precision("amount"))