fix: show correct variance for durations with no vouchers
diff --git a/erpnext/selling/report/sales_partner_target_variance_based_on_item_group/item_group_wise_sales_target_variance.py b/erpnext/selling/report/sales_partner_target_variance_based_on_item_group/item_group_wise_sales_target_variance.py
index d4e704a..42bdf57 100644
--- a/erpnext/selling/report/sales_partner_target_variance_based_on_item_group/item_group_wise_sales_target_variance.py
+++ b/erpnext/selling/report/sales_partner_target_variance_based_on_item_group/item_group_wise_sales_target_variance.py
@@ -197,6 +197,8 @@
 				):
 					details[p_key] += r.get(qty_or_amount_field, 0)
 					details[variance_key] = details.get(p_key) - details.get(target_key)
+				else:
+					details[variance_key] = details.get(p_key) - details.get(target_key)
 
 			details["total_achieved"] += details.get(p_key)
 			details["total_variance"] = details.get("total_achieved") - details.get("total_target")