handle panics in renderer somewhat more gracefully

src/window.rs

@@ -171,11 +171,17 @@ pub fn ui_loop() {
                 let frame_start = Instant::now();
 
                 if REDRAW_SCHEDULER.should_draw() {
+                    if let Err(err) = panic::catch_unwind(|| {
                         skulpin_renderer.draw(&window, |canvas, coordinate_system_helper| {
                             if renderer.draw(canvas, coordinate_system_helper) {
                                 handle_new_grid_size(window.inner_size(), &renderer)
                             }
                         }).ok();
+                    }) {
+                        println!("Render failed. Closing app");
+                        *control_flow = ControlFlow::Exit;
+                        return;
+                    }
                 }
 
                 *control_flow = ControlFlow::WaitUntil(frame_start + Duration::from_secs_f32(1.0 / 60.0));