Null issue fixed in gstr reports
diff --git a/erpnext/regional/report/gstr_1/gstr_1.py b/erpnext/regional/report/gstr_1/gstr_1.py
index 96c55ff..79d6e12 100644
--- a/erpnext/regional/report/gstr_1/gstr_1.py
+++ b/erpnext/regional/report/gstr_1/gstr_1.py
@@ -109,8 +109,8 @@
 		customers = frappe.get_all("Customer", filters={"customer_type": self.customer_type})
 
 		if self.filters.get("type_of_business") ==  "B2B":
-			conditions += " and invoice_type != 'Export' and is_return != 1 and customer in ('{0}')".\
-				format("', '".join([frappe.db.escape(c.name) for c in customers]))
+			conditions += """ and ifnull(invoice_type, '') != 'Export' and is_return != 1
+				and customer in ('{0}')""".format("', '".join([frappe.db.escape(c.name) for c in customers]))
 
 		if self.filters.get("type_of_business") in ("B2C Large", "B2C Small"):
 			b2c_limit = frappe.db.get_single_value('GSt Settings', 'b2c_limit')
diff --git a/erpnext/regional/report/gstr_2/gstr_2.py b/erpnext/regional/report/gstr_2/gstr_2.py
index 679e567..0a2e968 100644
--- a/erpnext/regional/report/gstr_2/gstr_2.py
+++ b/erpnext/regional/report/gstr_2/gstr_2.py
@@ -84,7 +84,7 @@
 					conditions += opts[1]
 
 		if self.filters.get("type_of_business") ==  "B2B":
-			conditions += "and invoice_type != 'Export' and is_return != 1 "
+			conditions += "and ifnull(invoice_type, '') != 'Export' and is_return != 1 "
 
 		elif self.filters.get("type_of_business") ==  "CDNR":
 			conditions += """ and is_return = 1 """