Can't get placeholderView .isPlaceHolder(true) working.

Code Block 
import WidgetKit
import SwiftUI
import Intents
struct Provider: TimelineProvider {
    public func snapshot(with context: Context, completion: @escaping (SimpleEntry) -> ()) {
        let entry = SimpleEntry(date: Date(), character: .panda)
        completion(entry)
    }
    public func timeline(with context: Context, completion: @escaping (Timeline<Entry>) -> ()) {
        let entries: [SimpleEntry] = [SimpleEntry(date: Date(), character: .panda)]
        let timeline = Timeline(entries: entries, policy: .atEnd)
        completion(timeline)
    }
}
struct SimpleEntry: TimelineEntry {
    public let date: Date
    let character: CharacterDetail
}
struct PlaceholderView : View {
    var body: some View {
        AvatarView(.panda)
        .isPlaceHolder(true) /* ERROR - Value of type 'AvatarView' has no member 'isPlaceHolder' */
    }
}
struct EmojiRangerWidgetEntryView : View {
    var entry: Provider.Entry
    var body: some View {
        AvatarView(entry.character)
    }
}
@main
struct EmojiRangerWidget: Widget {
    private let kind: String = "EmojiRangerWidget"
    public var body: some WidgetConfiguration {
        StaticConfiguration(kind: kind, provider: Provider(), placeholder: PlaceholderView()) { entry in
            EmojiRangerWidgetEntryView(entry: entry)
        }
        .configurationDisplayName("Emoji Rangers Detail")
        .description("Keep track of your favorite emoji ranger.")
        .supportedFamilies([.systemSmall])
    }
}
struct EmojiRangerWidget_Previews: PreviewProvider {
    static var previews: some View {
        Group {
            AvatarView(.panda )
                .previewContext(WidgetPreviewContext(family: .systemSmall))
            PlaceholderView()
                .previewContext(WidgetPreviewContext(family: .systemSmall))
        }
    }
}