ERROR FirebaseError: Expected type '_Query', but it was: a custom _CollectionReference object in 21.0.0-rc.0

# Issue

Upgraded to the release candidate and using the following collection subscription:

``` typescript
collectionData(collection(firestore, `users/${u.uid}/devices`), {
idField: 'id',
})
```

# Error

ERROR FirebaseError: Expected type '_Query', but it was: a custom _CollectionReference object

# Analysis

Not sure how to provide more detail on this, but it seems to be during a cast to Query in the `onSnapshot` handler.

Start by reproducing the collectionData example on 21.0.0-rc.0, then inspect the onSnapshot handler and its cast to Query. Done means the collection subscription no longer raises the FirebaseError for a CollectionReference; add or update coverage for this case if the repository exposes a relevant test location.

Written by the indexing model from the issue text.