Minor issues(handlers, scan)

[Luckas]

Hi there! It's the first time I'm really trying your app and I've encountered some small issues. Unfortunately, I can't work on a fork of your project and make a PR because of my current hardware but I hope this issue helps.

• The TUI player panics when trying to access empty fields due to the handlers:

The Enter events should check if the indexed field is valid

  Key::Enter => {
         if let Some(artist) = app.artist_table.artist.get(app.artist_table.selected_index) {
                app.dispatch(IoEvent::GetArtist(artist.id.clone()));
                app.push_navigation_stack(RouteId::Artist, ActiveBlock::ArtistBlock);
         }
  }

• The enter key doesn't work in the TUI player if a song is currently playing,I can't select other songs

• When exiting the TUI player this shows up (https://users.rust-lang.org/t/tokio-panics-during-shutdown/90250/2):

• Deleted songs still appear after re-scaning

OS: Fedora37
music-player version: v0.2.0-alpha.13