make buildObjectDef more robust (#1053)
make buildObjectDef more robust (#1053)

* test handle introspected schema with invalidly null interfaces

* Reformat test to more clearly indicate "missing"

tgriesser/graphql-js,jjergus/graphql-js,graphql/graphql-js,graphql/graphql-js,enaqx/graphql-js,jjergus/graphql-js,enaqx/graphql-js,graphql/graphql-js,tgriesser/graphql-js,enaqx/graphql-js