fix: NoneType has no len() (#24600)

diff --git a/erpnext/regional/india/e_invoice/utils.py b/erpnext/regional/india/e_invoice/utils.py
index e64be4b..5f701f2 100644
--- a/erpnext/regional/india/e_invoice/utils.py
+++ b/erpnext/regional/india/e_invoice/utils.py
@@ -23,7 +23,7 @@
 	invalid_doctype = doc.doctype != 'Sales Invoice'
 	invalid_supply_type = doc.get('gst_category') not in ['Registered Regular', 'SEZ', 'Overseas', 'Deemed Export']
 	company_transaction = doc.get('billing_address_gstin') == doc.get('company_gstin')
-	no_taxes_applied = len(doc.get('taxes')) == 0
+	no_taxes_applied = len(doc.get('taxes', [])) == 0
 
 	if not einvoicing_enabled or invalid_doctype or invalid_supply_type or company_transaction or no_taxes_applied:
 		return