Error: attempt to set an attribute on NULL

[leeper]

As described in #3 (#3 (comment)), applying class "sm_response" fails when there are NULL responses.

Error in lapply(content$data, class<-, "sm_response") : 
attempt to set an attribute on NULL

This might be caused by the fact that the content$status == 0

any idea how to overcome this?

Output by API Console:

{
"status": 0,
"data": [
null,
{
"respondent_id": "3707528732",
"questions": [
{
"answers": [
{
"text": "33",
"row": "8512740564"
},
{
"text": "33",
"row": "8512740565"
},