Testing is complete!! And a nice build runner script to boot

backend/lib/service/db_access.dart

@@ -8,9 +8,9 @@ final log = Logger('Db');
 class Db {
   static final _db = AppDatabase();
 
-  static Future<User> getUser(String uuid) {
+  static Future<User?> getUserById(String uuid) {
     log.finer('Getting user $uuid');
-    return _db.managers.users.filter((f) => f.uuid.equals(uuid)).getSingle();
+    return _db.managers.users.filter((f) => f.uuid.equals(uuid)).getSingleOrNull();
   }
 
   static Future<User?> createUser({required String username, required String roomCode}) async {
@@ -32,14 +32,21 @@ class Db {
     });
   }
 
-  static Future<GameRoom> createRoom({required String roomCode}) => _db.managers.gameRooms
-          .createReturning(
+  static Future<GameRoom?> createRoom({required String roomCode}) => _db.managers.gameRooms
+          .createReturningOrNull(
         (o) => o(createdAt: Value(DateTime.now()), status: GameStatus.open, uuid: const Uuid().v4(), code: roomCode),
       )
           .catchError(
         (Object err) {
           log.severe('Failed to create room', err, StackTrace.current);
-          throw Exception(err.toString());
+          return null;
         },
       );
+
+  static Future<GameRoom?> getRoomByCode(String? roomCode) async {
+    final room = await _db.managers.gameRooms
+        .filter((f) => f.code.equals(roomCode) & f.status.isIn([GameStatus.open, GameStatus.running]))
+        .getSingleOrNull();
+    return room;
+  }
 }