`game_template` fix up exhaustive checks (#1853)

## Pre-launch Checklist

- [x] I read the [Flutter Style Guide] _recently_, and have followed its
advice.
- [x] I signed the [CLA].
- [x] I read the [Contributors Guide].
- [x] I updated/added relevant documentation (doc comments with `///`).
- [ ] All existing and new tests are passing.

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<!-- Links -->
[Flutter Style Guide]:
https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo
[CLA]: https://cla.developers.google.com/
[Discord]: https://github.com/flutter/flutter/wiki/Chat
[Contributors Guide]:
https://github.com/flutter/samples/blob/main/CONTRIBUTING.md

game_template/lib/src/audio/audio_controller.dart

@@ -220,6 +220,8 @@ class AudioController {
             "Music should never be 'completed' as it's either not playing "
             "or looping forever.");
         await _playFirstSongInPlaylist();
+      default:
+        _log.warning('Unhandled PlayerState: ${_musicPlayer.state}');
     }
   }
 

tool/flutter_ci_script_master.sh

@@ -43,8 +43,7 @@ declare -ar PROJECT_NAMES=(
     "experimental/web_dashboard"
     "flutter_maps_firestore"
     "form_app"
-    # TODO(DomesticMouse): The type 'AppLifecycleState' is not exhaustively matched by the switch cases since it doesn't match 'AppLifecycleState.hidden'.
-    # "game_template"
+    "game_template"
     "google_maps"
     "infinite_list"
     "ios_app_clip"