(snap-backed-graphql-2) Make DauphinSolid's odd dual-state more explicit
Right now DauphinSolid is an odd class. It can be constructed
without specifying some of its arguments around dependencies. In this
state, the graphql queries will happily return and say that a specific
input or output of that solid in fact has no dependencies, which is not
true. Essentially in one mode DauphinSolid is being used for "header"
information only where one cannot explore through its inputs and outputs
to find dependencies.
This diff makes this current dual-state more explicit and, additionally,
makes it so the graphql queries explicity fail if cannot return
Test Plan: BK. Click around dagit.
Reviewers: alangenfeld, sashank, themissinghlink
Reviewed By: themissinghlink
Differential Revision: https://dagster.phacility.com/D2288