Partial success between steps fails to run next step, even with Node id available

[JohnStarich]

Looks like now that we have support for partial successes (#212), there's some interesting edge cases in the query plan step evaluation. In this case, if we get a partial success we get back the Node id field but the dependent step doesn't run.

This is particularly problematic for array responses, where some nodes may fail but others may succeed. An error in one node shouldn't prevent the other nodes' fields from resolving.