Lensing a non-AppState type causes an error

main.rs

use druid::{AppLauncher, Widget, WidgetExt, WindowDesc, UnitPoint,
    Lens, Data, ExtEventSink, widget::{Flex, Label}};
use std::sync::Arc;
use std::rc::Rc;

#[derive(Clone, Data, Lens)]
struct AppState {
    pub event_sink: Arc<ExtEventSink>,
    pub current_avatar: Rc<Avatar>
}

#[derive(Clone, Default, Data, Lens)]
struct Avatar {
    accountId: u32,
    pub displayName: String,
    internalName: String,
    nameChangeFlag: bool,
    percentCompleteForNextLevel: u8,
    profileIconId: u32,
    puuid: String,
    rerollPoints: RerollPoints,
    unnamed: bool,
    xpSinceLastLevel: u32,
    xpUntilNextLevel: u32
}

#[derive(Clone, Default, Debug, Data)]
struct RerollPoints {
    currentPoints: u32,
    maxRolls: u32,
    numberOfRolls: u32,
    pointsCostToRoll: u32,
    pointsToReroll: u32
}

fn main() {
    let root_window = WindowDesc::new(build_root_widget);

    let launcher = AppLauncher::with_window(root_window);
    let app_state = AppState {
        event_sink: Arc::new(launcher.get_external_handle()),
        current_avatar: Rc::new(Avatar::default())
    };
    
    launcher
        .launch(app_state)
        .expect("launch failed");
}

fn build_root_widget() -> impl Widget<AppState> {
    let label = Label::raw()
        .lens(Avatar::displayName)
        .padding(4.);

    Flex::column()
        .with_child(label)
        .align_vertical(UnitPoint::CENTER)
}