The closure passed to `eframe::run_native` now returns a `Result`,
allowing you to return an error during app creation, which will be
returned to the caller of `run_native`.
This means you need to wrap your `Box::new(MyApp::new(…))` in an
`Ok(…)`.
* Closes https://github.com/emilk/egui/issues/4474
942fe4ab31