anchor.diff:  
         if (request.containsKey('method')) {
           final String method = request['method'];
  -        final Map<String, dynamic> params = request['params'];
  +        final Map<String, dynamic> params = request['params'] ?? {};
           _handleMethod(method, params);
         } else if (request.containsKey('id')) {
  -        _handleResponse(request['id'], request['result']);
  +        _handleResponse(request['id']!, request['result']);
         } else {
           print('Unable to parse API message from server:\n\n$msg');
         }
  
positive.code:     _lastNotification?.close();
    }
  
    Future<T> _callMethod<T>(String method, [Map<String, dynamic> params]) {
      final id = '${_nextRequestId++}';
      final json = jsonEncode({
        'jsonrpc': '2.0',
  
negative.code:   /// This is called once, sometime after the `DevToolsServerConnection`
    /// instance is created.
    void initFrameworkController() {
      frameworkController.onConnected.listen((vmServiceUri) {
        _notifyConnected(vmServiceUri);
      });
  