While export GSTR1 TypeError - NoneType’ object is not iterable

While executing GST1 Report - Error Shows as

Traceback (most recent call last):
File “/home/frappe/frappe-bench/apps/frappe/frappe/app.py”, line 60, in application
response = frappe.api.handle()
File “/home/frappe/frappe-bench/apps/frappe/frappe/api.py”, line 55, in handle
return frappe.handler.handle()
File “/home/frappe/frappe-bench/apps/frappe/frappe/handler.py”, line 21, in handle
data = execute_cmd(cmd)
File “/home/frappe/frappe-bench/apps/frappe/frappe/handler.py”, line 56, in execute_cmd
return frappe.call(method, **frappe.form_dict)
File “/home/frappe/frappe-bench/apps/frappe/frappe/init.py”, line 1036, in call
return fn(*args, **newargs)
File “/home/frappe/frappe-bench/apps/frappe/frappe/init.py”, line 511, in wrapper_fn
retval = fn(*args, **get_newargs(fn, kwargs))
File “/home/frappe/frappe-bench/apps/frappe/frappe/desk/query_report.py”, line 200, in run
result = generate_report_result(report, filters, user)
File “/home/frappe/frappe-bench/apps/frappe/frappe/desk/query_report.py”, line 75, in generate_report_result
res = frappe.get_attr(method_name)(frappe._dict(filters))
File “/home/frappe/frappe-bench/apps/erpnext/erpnext/regional/report/gstr_1/gstr_1.py”, line 14, in execute
return Gstr1Report(filters).run()
File “/home/frappe/frappe-bench/apps/erpnext/erpnext/regional/report/gstr_1/gstr_1.py”, line 52, in run
self.get_data()
File “/home/frappe/frappe-bench/apps/erpnext/erpnext/regional/report/gstr_1/gstr_1.py”, line 63, in get_data
row, taxable_value = self.get_row_data_for_invoice(inv, invoice_details, rate, items)
File “/home/frappe/frappe-bench/apps/erpnext/erpnext/regional/report/gstr_1/gstr_1.py”, line 119, in get_row_data_for_invoice
if self.item_tax_rate.get(invoice) and tax_rate in self.item_tax_rate.get(invoice, {}).get(item_code):
TypeError: argument of type ‘NoneType’ is not iterable