Do not panic on failed setting of GameOver state in AlienCakeAddict (#3411)

# Objective

- Tentatively fixes #2525.

## Solution

- The panic seems to occur when the game-over state occurs nearly instantly.
- Discard the `Result`, rather than panicking. We could probably handle this better, but I want to see if this works first. Ping @qarmin.

examples/game/alien_cake_addict.rs

@@ -308,7 +308,8 @@ fn spawn_bonus(
         commands.entity(entity).despawn_recursive();
         game.bonus.entity = None;
         if game.score <= -5 {
-            state.set(GameState::GameOver).unwrap();
+            // We don't particularly care if this operation fails
+            let _ = state.overwrite_set(GameState::GameOver);
             return;
         }
     }