Issue with 2.0

[Andi1986]

Hi @AbdoPrDZ,

thanks for the version update, however with the Version 2.0 im facing an issue with the auth headers beeing transformed to future map instead of normal map.
At some point in the lifecycle of opening the socket connection, the headers are apparently tried to be encoded, which does not work for a Closure which is why i need to downgrade unfortionately.

this is how i create the socket:

Echo.socket(
      '$apiUrl:${SocketIoConfig.port}',
      authHeaders: () async => {
        'Authorization': 'Bearer $token',
        'Content-Type': 'application/json',
        'Accept': 'application/json'
      },
      moreOptions: {
        'transports': ['websocket']
      },
    );

This is the error i get:

E/flutter (19494): [ERROR:flutter/runtime/dart_vm_initializer.cc(40)] Unhandled Exception: Converting object to an encodable object failed: Closure: () => Future<Map<String, String>>
E/flutter (19494): #0      _JsonStringifier.writeObject (dart:convert/json.dart:824:7)
E/flutter (19494): #1      _JsonStringifier.writeMap (dart:convert/json.dart:908:7)
E/flutter (19494): #2      _JsonStringifier.writeJsonValue (dart:convert/json.dart:863:21)
E/flutter (19494): #3      _JsonStringifier.writeObject (dart:convert/json.dart:815:9)
E/flutter (19494): #4      _JsonStringStringifier.printOn (dart:convert/json.dart:1024:17)
E/flutter (19494): #5      _JsonStringStringifier.stringify (dart:convert/json.dart:1005:5)
E/flutter (19494): #6      JsonEncoder.convert (dart:convert/json.dart:353:30)
E/flutter (19494): #7      JsonCodec.encode (dart:convert/json.dart:238:45)
E/flutter (19494): #8      Encoder.encodeAsString (package:socket_io_common/src/parser/parser.dart:89:19)
E/flutter (19494): #9      Encoder.encode (package:socket_io_common/src/parser/parser.dart:63:13)
E/flutter (19494): #10     Manager.packet (package:socket_io_client/src/manager.dart:350:34)
E/flutter (19494): #11     Socket.packet (package:socket_io_client/src/socket.dart:337:8)
E/flutter (19494): #12     Socket.sendConnectPacket (package:socket_io_client/src/socket.dart:361:5)
E/flutter (19494): #13     Socket.onopen (package:socket_io_client/src/socket.dart:352:7)
E/flutter (19494): #14     EventEmitter._emit.<anonymous closure> (package:socket_io_common/src/util/event_emitter.dart:44:14)
E/flutter (19494): #15     List.forEach (dart:core-patch/growable_array.dart:428:8)
E/flutter (19494): #16     EventEmitter._emit (package:socket_io_common/src/util/event_emitter.dart:43:11)
E/flutter (19494): #17     EventEmitter.emitReserved (package:socket_io_common/src/util/event_emitter.dart:57:47)
E/flutter (19494): #18     Manager.onopen (package:socket_io_client/src/manager.dart:247:5)
E/flutter (19494): #19     Manager.open.<anonymous closure> (package:socket_io_client/src/manager.dart:180:7)
E/flutter (19494): #20     EventEmitter._emit.<anonymous closure> (package:socket_io_common/src/util/event_emitter.dart:44:14)
E/flutter (19494): #21     List.forEach (dart:core-patch/growable_array.dart:428:8)
E/flutter (19494): #22     EventEmitter._emit (package:socket_io_common/src/util/event_emitter.dart:43:11)
E/flutter (19494): #23     EventEmitter.emitReserved (package:socket_io_common/src/util/event_emitter.dart:57:47)
E/flutter (19494): #24     Socket.onOpen (package:socket_io_client/src/engine/socket.dart:347:5)
E/flutter (19494): #25     Socket.onHandshake (package:socket_io_client/src/engine/socket.dart:418:5)
E/flutter (19494): #26     Socket.onPacket (package:socket_io_client/src/engine/socket.dart:382:11)
E/flutter (19494): #27     Socket.setTransport.<anonymous closure> (package:socket_io_client/src/engine/socket.dart:217:34)
E/flutter (19494): #28     EventEmitter._emit.<anonymous closure> (package:socket_io_common/src/util/event_emitter.dart:44:14)
E/flutter (19494): #29     List.forEach (dart:core-patch/growable_array.dart:428:8)
E/flutter (19494): #30     EventEmitter._emit (package:socket_io_common/src/util/event_emitter.dart:43:11)
E/flutter (19494): #31     EventEmitter.emitReserved (package:socket_io_common/src/util/event_emitter.dart:57:47)
E/flutter (19494): #32     Transport.onPacket (package:socket_io_client/src/engine/transport.dart:95:5)
E/flutter (19494): #33     Transport.onData (package:socket_io_client/src/engine/transport.dart:89:5)
E/flutter (19494): #34     IOWebSocketTransport.addEventListeners.<anonymous closure> (package:socket_io_client/src/engine/transport/io_websocket_transport.dart:59:7)
E/flutter (19494): #35     _RootZone.runUnaryGuarded (dart:async/zone.dart:1778:10)
E/flutter (19494): #36     _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:381:11)
E/flutter (19494): #37     _BufferingStreamSubscription._add (dart:async/stream_impl.dart:312:7)
E/flutter (19494): #38     _SyncStreamControllerDispatch._sendData (dart:async/stream_controller.dart:798:19)
E/flutter (19494): #39     _StreamController._add (dart:async/stream_controller.dart:663:7)
E/flutter (19494): #40     _StreamController.add (dart:async/stream_controller.dart:618:5)
E/flutter (19494): #41     new _WebSocketImpl._fromSocket.<anonymous closure> (dart:_http/websocket_impl.dart:1252:27)
E/flutter (19494): #42     _RootZone.runUnaryGuarded (dart:async/zone.dart:1778:10)
E/flutter (19494): #43     _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:381:11)
E/flutter (19494): #44     _BufferingStreamSubscription._add (dart:async/stream_impl.dart:312:7)
E/flutter (19494): #45     _SinkTransformerStreamSubscription._add (dart:async/stream_transformers.dart:67:11)
E/flutter (19494): #46     _EventSinkWrapper.add (dart:async/stream_transformers.dart:13:11)
E/flutter (19494): #47     _WebSocketProtocolTransformer._messageFrameEnd (dart:_http/websocket_impl.dart:348:23)
E/flutter (19494): #48     _WebSocketProtocolTransformer.add (dart:_http/websocket_impl.dart:238:46)
E/flutter (19494): #49     _SinkTransformerStreamSubscription._handleData (dart:async/stream_transformers.dart:115:24)
E/flutter (19494): #50     _HttpDetachedStreamSubscription._maybeScheduleData.<anonymous closure> (dart:_http/http_parser.dart:187:20)
E/flutter (19494): #51     _microtaskLoop (dart:async/schedule_microtask.dart:40:35)
E/flutter (19494): #52     _startMicrotaskLoop (dart:async/schedule_microtask.dart:49:5)