Hey Chip - thank you for the report. Even though at first this feels like a bug it's actually by design.

If Avo allows you to omit the key when a value should not be sent, it becomes all too easy to forget to send it when it should be sent. We've seen people forget about optional values many times and that's why the generated code requires the key to be present even when the value is omitted.

Does this make sense to you? We'd love your thoughts on this.