lencx/ChatGPT · error

[view:titlebar] Failed to get webview window

Error message

[view:titlebar] Failed to get webview window

What it means

Panic from win.get_webview("titlebar") returning None in the Resized handler. The titlebar webview is the first child added on macOS but the second on other platforms (setup.rs:149-157), and the handler expects all three labels to exist forever. None is returned before add_child(titlebar_view, ...) completes or after the webview is torn down during window destruction, so a resize at either boundary panics the event handler.

Source

Thrown at src-tauri/src/core/setup.rs:193

                    if let Err(e) = view.set_size(size) {
                        eprintln!("[view:size] Failed to set view size: {}", e);
                    }
                };

            win.on_window_event(move |event| {
                let conf = &AppConf::load(&handle).unwrap();
                let ask_mode_height = if conf.ask_mode { ASK_HEIGHT } else { 0.0 };
                let ask_height = (scale_factor * ask_mode_height).round() as u32;

                if let WindowEvent::Resized(size) = event {
                    let win = window_clone.lock().unwrap();

                    let main_view = win
                        .get_webview("main")
                        .expect("[view:main] Failed to get webview window");
                    let titlebar_view = win
                        .get_webview("titlebar")
                        .expect("[view:titlebar] Failed to get webview window");
                    let ask_view = win
                        .get_webview("ask")
                        .expect("[view:ask] Failed to get webview window");

                    #[cfg(target_os = "macos")]
                    {
                        set_view_properties(
                            &main_view,
                            LogicalPosition::new(0.0, TITLEBAR_HEIGHT),
                            PhysicalSize::new(
                                size.width,
                                size.height - (titlebar_height + ask_height),
                            ),
                        );
                        set_view_properties(
                            &titlebar_view,
                            LogicalPosition::new(0.0, 0.0),
                            PhysicalSize::new(size.width, titlebar_height),

View on GitHub (pinned to a6de9a8b61)

Solutions

  1. Use let-else/if-let for all three lookups and skip the relayout when any is missing
  2. Move handler registration after the platform-specific add_child block so children exist before events are processed
  3. Skip work on WindowEvent::Destroyed and early-return when size dimensions are degenerate
  4. Consider fetching all three labels once and bailing out as a group instead of three independent expects

Example fix

// before
let titlebar_view = win
    .get_webview("titlebar")
    .expect("[view:titlebar] Failed to get webview window");

// after
let Some(titlebar_view) = win.get_webview("titlebar") else {
    eprintln!("[view:titlebar] webview not ready; skipping resize");
    return;
};
Defensive patterns

Strategy: type-guard

Validate before calling

// verify the platform-ordered children exist before hooking events
if !webviews_attached(&win) {
    eprintln!("[setup] skipping resize handler; children missing");
    return;
}

Type guard

fn titlebar_attached(win: &tauri::Window) -> bool {
    win.get_webview("titlebar").is_some()
}

Try / catch

let Some(titlebar_view) = win.get_webview("titlebar") else {
    eprintln!("[view:titlebar] webview not ready; skipping resize");
    return;
};

Prevention

When it happens

Trigger: Resized fired during the gap between window creation and the non-macOS add_child(titlebar_view) call (titlebar is added second there, widening the race); Resized delivered during close/destroy after child webviews are dropped; the titlebar add_child .unwrap() at setup.rs:148/157 having failed so the label never got registered.

Common situations: Tiling WMs and snap layouts emitting Resized at startup/shutdown; the platform-specific add_child ordering difference (macOS adds titlebar first, Windows/Linux add ask first) making the bug appear OS-specific; DPI/scale-factor changes triggering early resize cascades.

Related errors

AI-assisted analysis of lencx/ChatGPT@a6de9a8b61 (2026-08-16). Data as JSON: /api/errors/a5b2248297fc0f03. Report an issue: GitHub.