When I create a schema with a query with name `test`, create a resolver for it, then change the name of query to `testA`, the resolver stays in DB. It is not visible in UI, but when server tries to reload with the new schema, it fails to do so:

[...] ERROR (48155 on ...): Error while reloading config

[...] ERROR (48155 on ...): Query.test defined in resolvers, but not in schema

    Error: Query.test defined in resolvers, but not in schema

[...] ERROR (48155 on ...): Will continue using the old config

We should probably remove resolvers for queries/mutations which disappear from schema.