Migrating from 2.2.2 to 3.0.2 not working

[RYOKSEC]

when i run the app it throws this error

I/flutter (31556): --LocalizeAndTranslate : deviceLocale(ar)
E/flutter (31556): [ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: FormatException: Unexpected character (at line 53, character 1)
E/flutter (22483): }
E/flutter (22483): ^
E/flutter (22483): 
E/flutter (22483): #0      _ChunkedJsonParser.fail (dart:convert-patch/convert_patch.dart:1394:5)
E/flutter (22483): #1      _ChunkedJsonParser.parse (dart:convert-patch/convert_patch.dart:918:20)
E/flutter (22483): #2      _parseJson (dart:convert-patch/convert_patch.dart:31:10)
E/flutter (22483): #3      JsonDecoder.convert (dart:convert/json.dart:505:36)
E/flutter (22483): #4      JsonCodec.decode (dart:convert/json.dart:153:41)
E/flutter (22483): #5      LocalizeAndTranslate.initLanguage (package:localize_and_translate/src/main.class.dart:107:20)
E/flutter (22483): <asynchronous suspension>
E/flutter (22483): #6      LocalizeAndTranslate.init (package:localize_and_translate/src/main.class.dart:87:13)
E/flutter (22483): <asynchronous suspension>
E/flutter (22483): #7      main (package:system/main.dart:17:20)
E/flutter (22483): #8      _runMainZoned.<anonymous closure>.<anonymous closure> (dart:ui/hooks.dart:241:25)
E/flutter (22483): #9      _rootRun (dart:async/zone.dart:1184:13)
E/flutter (22483): #10     _CustomZone.run (dart:async/zone.dart:1077:19)
E/flutter (22483): #11     _runZoned (dart:async/zone.dart:1619:10)
E/flutter (22483): #12     runZonedGuarded (dart:async/zone.dart:1608:12)
E/flutter (22483): #13     _runMainZoned.<anonymous closure> (dart:ui/hooks.dart:233:5)
E/flutter (22483): #14     _startIsolate.<anonymous closure> (dart:isolate-patch/isolate_patch.dart:301:19)
E/flutter (22483): #15     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:168:12)
E/flutter (22483): 

here is how i am initializing it

void main() async{
  WidgetsFlutterBinding.ensureInitialized();
  await translator.init(
    localeDefault: LocalizationDefaultType.device,
    languagesList: <String>['ar', 'en'],
    assetsDirectory: 'assets/langs/',
  );


  SystemChrome.setPreferredOrientations(
      [DeviceOrientation.portraitUp , DeviceOrientation.portraitDown])
      .then((_) => runApp(
     Phoenix(
      child: LocalizedApp(
        child: BillingSystem(),
        ),
      )
    ),
  );
}

class BillingSystem extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      localizationsDelegates: translator.delegates, // Android + iOS Delegates
      locale: translator.locale, // Active locale
      supportedLocales: translator.locals(),
      title: 'Billing System',
      theme: ThemeData(
        primaryColor: Color(0xff146eb4),
          textTheme:
          TextTheme(
              headline6: TextStyle(color: Colors.black , fontSize: 22.0 , fontWeight: FontWeight.w500),
              bodyText1: TextStyle(color: Colors.black , fontSize: 16) ,
          )
      ),
      home: AuthenticationPage(),
    );
  }
}

[RYOKSEC]

It was working perfectly in 2.2.2 until suddenly it threw the same error so that i had to upgrade but its not working either

[RYOKSEC]

the problem was caused by the translation files so i checked them and i found that each of them ends with , when removed this fixed the problem it was an error caused by my IDE because it usually inserts a comma at the end of the line when you insert new line in json files

problem example :
"cart" : "Cart",
"add_to_cart" : "Add To Cart",
}

Fix :
"cart" : "Cart",
"add_to_cart" : "Add To Cart" <--here just remove the comma
}