## Summary:
We guarantee that we never return a nil response, so you can safely do
```
resp, err := myQuery(...)
return resp.Field.SubField, err
```
And furthermore, if the error was a GraphQL error, `resp` may even be
nonzero; other, non-failing fields may be set. (This depends on the
server, of course.) But we weren't testing either of those. Now we do.
## Test plan:
make check
Author: benjaminjkraft
Reviewers: jvoll, aberkan, dnerdy, MiguelCastillo, mahtabsabet
Required Reviewers:
Approved By: jvoll
Checks: ✅ Test (1.17), ✅ Test (1.16), ✅ Test (1.15), ✅ Test (1.14), ✅ Lint, ✅ Test (1.17), ✅ Test (1.16), ✅ Test (1.15), ✅ Test (1.14), ✅ Lint
Pull Request URL: https://github.com/Khan/genqlient/pull/83
