IsolateMaster constructor Null safety

Implementation

IsolateMaster(IsolateBridgeEntryFunc cb) {
  _status = IsoBridgeStatus.init;
  _entryFunc = cb;
  _receivePortForUxIsolate = RawReceivePort(_processAction);
  _sendPortForExecIsolate = _receivePortForUxIsolate
      .sendPort; //Temporary assignment for early callers
  _errors = <IsoactionInternalError>[];
  _pingLastStamp = DateTime.now();
  _pingCount = 0;
  Timer.run(initialize);
}