Fixes issue where base types file is not referenced

[mvestergaard]

This is a suggestion to fix the issue mentioned in #2069 (comment)

When a query only contains a fragment spread:

query {
  user {
    ...UserFragment
  }
}

as opposed to

query {
  user {
    id
    ...UserFragment
  }
}

The import of the main types file, i.e. import * as Types from '../types' was not included.

[dotansimha]

Thank you @mvestergaard !
I think @mxstbr had the same issue recently.