fix: create sales order

Getting error while clicking create sales order button from quotation

Taceback (most recent call last):
  File "apps/frappe/frappe/app.py", line 66, in application
    response = frappe.api.handle()
  File "apps/frappe/frappe/api.py", line 54, in handle
    return frappe.handler.handle()
  File "apps/frappe/frappe/handler.py", line 45, in handle
    data = execute_cmd(cmd)
  File "apps/frappe/frappe/handler.py", line 83, in execute_cmd
    return frappe.call(method, **frappe.form_dict)
  File "apps/frappe/frappe/__init__.py", line 1607, in call
    return fn(*args, **newargs)
  File "apps/frappe/frappe/model/mapper.py", line 36, in make_mapped_doc
    return method(source_name)
  File "apps/erpnext/erpnext/selling/doctype/quotation/quotation.py", line 263, in make_sales_order
    return _make_sales_order(source_name, target_doc)
  File "apps/erpnext/erpnext/selling/doctype/quotation/quotation.py", line 333, in _make_sales_order
    doclist = get_mapped_doc(
  File "apps/frappe/frappe/model/mapper.py", line 144, in get_mapped_doc
    postprocess(source_doc, target_doc)
  File "apps/erpnext/erpnext/selling/doctype/quotation/quotation.py", line 291, in set_missing_values
    for d in customer.get("sales_team"):
TypeError: 'NoneType' object is not iterable
diff --git a/erpnext/selling/doctype/quotation/quotation.py b/erpnext/selling/doctype/quotation/quotation.py
index 693fc92..0cab21f 100644
--- a/erpnext/selling/doctype/quotation/quotation.py
+++ b/erpnext/selling/doctype/quotation/quotation.py
@@ -288,7 +288,7 @@
 			)
 
 		# sales team
-		for d in customer.get("sales_team"):
+		for d in customer.get("sales_team", []):
 			target.append(
 				"sales_team",
 				{