SproutCore’s SC.Response was recently rewritten and I patched it to avoid an exception to be thrown when a malformed JSON string was parsed. The standard way to write your data source didFetch method is now:
didFetch: function(response, params) {
var results, query = params.query;
if (SC.ok(response) && SC.ok(results = response.get('body'))) {
...
} else {
store.dataSourceDidErrorQuery(query);
}
}