Bug. Null check operator used on a null value. When centrifugal client close

[rgrunin]

return _socket!.close();

https://github.com/centrifugal/centrifuge-dart/blame/53dc5a90a97831faafa5bd60f2c8f3237f6a1b6f/lib/src/transport.dart#L84

#0      Transport.close (package:centrifuge/src/transport.dart:84:19)
#1      ClientImpl.disconnect (package:centrifuge/src/client.dart:207:22)
#2      _CentrifugeConnectMixin.close (package:magistral/src/features/socket_connector/data/centrifuge_connector.dart:167:13)
<asynchronous suspension>

[Alexander Emelin]

Hello, @r-oman-G ! This is already fixed as of 0.8.0 I suppose.