panicked at 'attempt to subtract with overflow' when deserializing spa pod

Trying to deserialize Props param data from pw results in:

spa_pod { size: 296, type_: 15 } @ 0x55ff54cf85c0
thread '<unnamed>' panicked at 'attempt to subtract with overflow', ~/.config/cargo/registry/src/github.com-1ecc6299db9ec823/libspa-0.4.1/src/pod/deserialize.rs:396:23
   3: libspa::pod::deserialize::PodDeserializer::deserialize_str
             at ~/.config/cargo/registry/src/github.com-1ecc6299db9ec823/libspa-0.4.1/src/pod/deserialize.rs:396:23
   4: libspa::pod::deserialize::PodDeserializer::deserialize_any
             at /home/arc/.config/cargo/registry/src/github.com-1ecc6299db9ec823/libspa-0.4.1/src/pod/deserialize.rs:796:41
   5: <libspa::pod::Value as libspa::pod::deserialize::PodDeserialize>::deserialize
             at ~/.config/cargo/registry/src/github.com-1ecc6299db9ec823/libspa-0.4.1/src/pod.rs:606:9
   6: libspa::pod::deserialize::StructPodDeserializer::deserialize_field
             at ~/.config/cargo/registry/src/github.com-1ecc6299db9ec823/libspa-0.4.1/src/pod/deserialize.rs:977:34
   7: <libspa::pod::deserialize::ValueVisitor as libspa::pod::deserialize::Visitor>::visit_struct
             at ~/.config/cargo/registry/src/github.com-1ecc6299db9ec823/libspa-0.4.1/src/pod/deserialize.rs:1520:33
   8: libspa::pod::deserialize::PodDeserializer::deserialize_struct
             at ~/.config/cargo/registry/src/github.com-1ecc6299db9ec823/libspa-0.4.1/src/pod/deserialize.rs:542:19
   9: libspa::pod::deserialize::PodDeserializer::deserialize_any
             at ~/.config/cargo/registry/src/github.com-1ecc6299db9ec823/libspa-0.4.1/src/pod/deserialize.rs:801:41
  10: <libspa::pod::Value as libspa::pod::deserialize::PodDeserialize>::deserialize
             at ~/.config/cargo/registry/src/github.com-1ecc6299db9ec823/libspa-0.4.1/src/pod.rs:606:9
  11: libspa::pod::deserialize::ObjectPodDeserializer::deserialize_property
             at ~/.config/cargo/registry/src/github.com-1ecc6299db9ec823/libspa-0.4.1/src/pod/deserialize.rs:1052:34
  12: <libspa::pod::deserialize::ValueVisitor as libspa::pod::deserialize::Visitor>::visit_object
             at ~/.config/cargo/registry/src/github.com-1ecc6299db9ec823/libspa-0.4.1/src/pod/deserialize.rs:1533:47
  13: libspa::pod::deserialize::PodDeserializer::deserialize_object
             at ~/.config/cargo/registry/src/github.com-1ecc6299db9ec823/libspa-0.4.1/src/pod/deserialize.rs:586:19
  14: libspa::pod::deserialize::PodDeserializer::deserialize_any
             at ~/.config/cargo/registry/src/github.com-1ecc6299db9ec823/libspa-0.4.1/src/pod/deserialize.rs:803:41
  15: <libspa::pod::Value as libspa::pod::deserialize::PodDeserialize>::deserialize
             at ~/.config/cargo/registry/src/github.com-1ecc6299db9ec823/libspa-0.4.1/src/pod.rs:606:9
  16: libspa::pod::deserialize::PodDeserializer::deserialize_from
             at ~/.config/cargo/registry/src/github.com-1ecc6299db9ec823/libspa-0.4.1/src/pod/deserialize.rs:242:9
  17: libspa::pod::deserialize::PodDeserializer::deserialize_ptr
             at ~/.config/cargo/registry/src/github.com-1ecc6299db9ec823/libspa-0.4.1/src/pod/deserialize.rs:258:19

Here's the actual expected object, constructed using a spa_pod_parser instead of nom:

Object {
    type: Spa:Pod:Object:Param:Props (262146),
    id: "Props" (2),
    properties: [
        Property {
            key: "volume" (65539),
            flags: (empty),
            value: Float(1.0),
        },
        Property {
            key: "mute" (65540),
            flags: (empty),
            value: Bool(false),
        },
        Property {
            key: "channelVolumes" (65544),
            flags: (empty),
            value: ValueArray(Float([0.3890102, 0.3890102])),
        },
        Property {
            key: "channelMap" (65547),
            flags: (empty),
            value: Ids(
                [
                    "FL" (3),
                    "FR" (4),
                ],
            ),
        },
        Property {
            key: "softMute" (65551),
            flags: (empty),
            value: Bool(false),
        },
        Property {
            key: "softVolumes" (65552),
            flags: (empty),
            value: ValueArray(Float([1.0, 1.0])),
        },
        Property {
            key: "monitorMute" (65548),
            flags: (empty),
            value: Bool(false),
        },
        Property {
            key: "monitorVolumes" (65549),
            flags: (empty),
            value: ValueArray(Float([1.0, 1.0])),
        },
        Property {
            key: "params" (524289),
            flags: (empty),
            value: Struct(
                [
                    String("monitor.channel-volumes"),
                    Bool(false),
                ],
            ),
        },
    ],
}

(btw, libspa::pod::deserialize::PodDeserializer should really be a trait instead of a struct so that parsers can be implemented externally as a proper analogue to a serde::Deserializer; likewise for PodSerializer)