chore: resolve errors in test
diff --git a/erpnext/accounts/doctype/tax_withholding_category/tax_withholding_category.py b/erpnext/accounts/doctype/tax_withholding_category/tax_withholding_category.py
index a9d870d..b834d14 100644
--- a/erpnext/accounts/doctype/tax_withholding_category/tax_withholding_category.py
+++ b/erpnext/accounts/doctype/tax_withholding_category/tax_withholding_category.py
@@ -133,7 +133,7 @@
 def get_cost_center(inv):
 	cost_center = frappe.get_cached_value("Company", inv.company, "cost_center")
 
-	if len(inv.get("taxes")) > 0:
+	if len(inv.get("taxes", [])) > 0:
 		cost_center = inv.get("taxes")[0].cost_center
 
 	return cost_center