Getting TypeError: 'NoneType' object is not subscriptable

App Versions

{
“erpnext”: “15.9.1”,
“frappe”: “15.8.1”,
“frappe_whatsapp”: “0.0.2”,
“hrms”: “15.8.0”,
“india_compliance”: “15.4.0”,
“payments”: “0.0.1”
}

Route

Form/Payment Entry/new-payment-entry-wbiehzaqoq

Traceback

Traceback (most recent call last):
File “apps/frappe/frappe/app.py”, line 110, in application
response = frappe.api.handle(request)
File “apps/frappe/frappe/api/init.py”, line 49, in handle
data = endpoint(**arguments)
File “apps/frappe/frappe/api/v1.py”, line 36, in handle_rpc_call
return frappe.handler.handle()
File “apps/frappe/frappe/handler.py”, line 49, in handle
data = execute_cmd(cmd)
File “apps/frappe/frappe/handler.py”, line 85, in execute_cmd
return frappe.call(method, **frappe.form_dict)
File “apps/frappe/frappe/init.py”, line 1689, in call
return fn(*args, **newargs)
File “apps/frappe/frappe/utils/typing_validations.py”, line 31, in wrapper
return func(*args, **kwargs)
File “apps/frappe/frappe/desk/form/save.py”, line 39, in savedocs
doc.save()
File “apps/frappe/frappe/model/document.py”, line 334, in save
return self._save(*args, **kwargs)
File “apps/frappe/frappe/model/document.py”, line 356, in _save
return self.insert()
File “apps/frappe/frappe/model/document.py”, line 286, in insert
self.run_before_save_methods()
File “apps/frappe/frappe/model/document.py”, line 1084, in run_before_save_methods
self.run_method(“validate”)
File “apps/frappe/frappe/model/document.py”, line 953, in run_method
out = Document.hook(fn)(self, *args, **kwargs)
File “apps/frappe/frappe/model/document.py”, line 1319, in composer
return composed(self, method, *args, **kwargs)
File “apps/frappe/frappe/model/document.py”, line 1301, in runner
add_to_return_value(self, fn(self, *args, **kwargs))
File “apps/frappe/frappe/model/document.py”, line 950, in fn
return method_object(*args, **kwargs)
File “apps/erpnext/erpnext/accounts/doctype/payment_entry/payment_entry.py”, line 76, in validate
self.set_liability_account()
File “apps/erpnext/erpnext/accounts/doctype/payment_entry/payment_entry.py”, line 138, in set_liability_account
liability_account = get_party_account(
TypeError: ‘NoneType’ object is not subscriptable