made icon optional and default to empty string & adjust all game instances

test/db_tests/entities/game_test.dart

@@ -44,7 +44,6 @@ void main() {
         ruleset: Ruleset.highestScore,
         description: 'A board game about real estate',
         color: GameColor.orange,
-        icon: '',
       );
     });
   });
@@ -54,7 +53,6 @@ void main() {
   });
 
   group('Game Tests', () {
-
     // Verifies that getAllGames returns an empty list when the database has no games.
     test('getAllGames returns empty list when no games exist', () async {
       final allGames = await database.gameDao.getAllGames();
@@ -106,7 +104,7 @@ void main() {
     // Verifies that getGameById throws a StateError when the game doesn't exist.
     test('getGameById throws exception for non-existent game', () async {
       expect(
-            () => database.gameDao.getGameById(gameId: 'non-existent-id'),
+        () => database.gameDao.getGameById(gameId: 'non-existent-id'),
         throwsA(isA<StateError>()),
       );
     });
@@ -134,7 +132,12 @@ void main() {
 
     // Verifies that a game with empty optional fields can be added and retrieved.
     test('addGame handles game with null optional fields', () async {
-      final gameWithNulls = Game(name: 'Simple Game', ruleset: Ruleset.lowestScore, description: 'A simple game', color: GameColor.green, icon: '');
+      final gameWithNulls = Game(
+        name: 'Simple Game',
+        ruleset: Ruleset.lowestScore,
+        description: 'A simple game',
+        color: GameColor.green,
+      );
       final result = await database.gameDao.addGame(game: gameWithNulls);
       expect(result, true);
 
@@ -419,9 +422,7 @@ void main() {
 
     // Verifies that getGameCount updates correctly after deleting a game.
     test('getGameCount updates correctly after deletion', () async {
-      await database.gameDao.addGamesAsList(
-        games: [testGame1, testGame2],
-      );
+      await database.gameDao.addGamesAsList(games: [testGame1, testGame2]);
 
       final countBefore = await database.gameDao.getGameCount();
       expect(countBefore, 2);
@@ -461,7 +462,6 @@ void main() {
         ruleset: Ruleset.multipleWinners,
         description: 'Description with émojis 🎮🎲',
         color: GameColor.purple,
-        icon: '',
       );
       await database.gameDao.addGame(game: specialGame);
 
@@ -478,7 +478,6 @@ void main() {
         name: '',
         ruleset: Ruleset.singleWinner,
         description: '',
-        icon: '',
         color: GameColor.red,
       );
       await database.gameDao.addGame(game: emptyGame);
@@ -500,7 +499,6 @@ void main() {
         description: longString,
         ruleset: Ruleset.multipleWinners,
         color: GameColor.yellow,
-        icon: '',
       );
       await database.gameDao.addGame(game: longGame);