Querying with != and not-in throws error with Query.where in firestore

I tried using != and not-in as params to Query.where as described here:

    db.collection("users")
      .where(firebase.firestore.FieldPath.documentId(), "!=", curUser.uid)
      .get()
      .then((snapshot) => {
         ...
      });

But I'm getting the following error:

Invalid value "!=" provided to function Query.where() for its second argument. Acceptable values: <, <=, ==, >=, >, array-contains, in, array-contains-any

I even tried this on an ordinary non-document id field and it gives the same error.

I am using the node package firebase version 7.9.0.