Error: Query root type must be provided #610

I'm receiving the error:

```
Error: Query root type must be provided
```

Here is my schema:

schema.graphql
```
schema {
query: ClientQuery
...
}

type ClientQuery {
...
}
```

I am importing it with `graphql-importer`

```
import { importSchema } from 'graphql-import'

const baseTypeDefs = importSchema('../pg-fresh-client/schema/schema.graphql')
```

Shouldn't this be valid?

Start with the shown schema.graphql and the importSchema('../pg-fresh-client/schema/schema.graphql') call; reproduce the reported error using the supplied SDL and inspect the graphql-import parsing entry point. Confirm whether this schema should be accepted and, if it is a bug, add a focused regression test showing the expected result.

Written by the indexing model from the issue text.