arrays are not supported by `humility hiffy`

I have an Idol function specified by

        "get_power_state": (
            doc: "Get the power state of all ports.",
            reply: Result(
                ok: "[PowerState; 32]",
                err: CLike("TransceiversError"),
            ),
            encoding: Ssmarshal
        ),

But when I try to use that I get a runtime error from humility hiffy

humility hiffy failed: no type for Transceivers.get_power_state: Result { ok: AttributedTy { ty: Ty("[PowerState; 32]"), recv: FromBytes }, err: CLike(Ty("TransceiversError")) } (as basetype: "expected [PowerState; 32] to be a basetype"; as enum: "expected enum not found"; as struct: "expected structure not found"; as REPLY: "expected structure Transceivers_get_power_state_REPLY not found")

Start with the humility hiffy command and trace how the Result { ok: "[PowerState; 32]" ... } reply type is classified, using the reported runtime error as the initial failure. Done means an Idol reply containing a fixed-size array such as [PowerState; 32] is accepted instead of producing the basetype, enum, struct, or REPLY errors.