fix error when there are no permissions to validate

modules/core_project_factory/scripts/preconditions/preconditions.py

@@ -112,14 +112,23 @@ def __init__(self, org_id, shared_vpc=False, parent=False):
             self.permissions += self.PARENT_PERMISSIONS
 
     def validate(self, credentials):
+        body = {"permissions": self.permissions}
+        resource = "organizations/" + self.org_id
+
+        # no permissions to validate
+        if len(self.permissions) == 0:
+            return {
+                "type": "Service account permissions on organization",
+                "name": "organizations/" + self.org_id,
+                "satisfied": [],
+                "unsatisfied": []
+            }
+
         service = discovery.build(
             'cloudresourcemanager', 'v1',
             credentials=credentials
         )
 
-        body = {"permissions": self.permissions}
-        resource = "organizations/" + self.org_id
-
         request = service.organizations().testIamPermissions(
             resource=resource,
             body=body)