[tests]: Not all $refs can be resolved

[MikeRalphson]

Shows up in the postman fixture. A $ref exists to #/components/schemas/Error but no such schema object exists. An empty schema object would suffice at the correct structural location.

[kevinswiber]

Ah, yes. This $ref exists because it's a request input for submitting an OpenAPI definition to one of the API endpoints. What should we do here? I'm inclined to leave it as-is and list it as a known issue.

[MikeRalphson]

You're right, I'm picking up a $ref within an example, which is a bug on my side. I think we can close.