In debugging https://github.com/uber/phabricator-jenkins-plugin/issues/30#issuecomment-110588285, we noticed that the response type was `[]` instead of `{}`, additionally no error message was provided.
repro steps. using a conduit token with a user who doesn't have permission to a repo:
```lang=bash
echo '{"ids": [6]}' | arc call-conduit differential.querydiffs --conduit-token=api-... | python -mjson.tool
```
```lang=json
{
"error": null,
"errorMessage": null,
"response": []
}
```
In the meantime, i will add extra logic to check the object type in our jenkins plugin, but i assume this is unintended behavior.