anchor.diff:  
     final ResourceProvider? resourceProvider;
   
  -  _PSNode(YamlNode node, this.resourceProvider)
  +  _PSNode(YamlScalar node, this.resourceProvider)
         : text = node.value?.toString(),
           span = node.span;
   
  
positive.code:   return null;
  }
  
  PSNodeList? _processList(
      YamlScalar key, YamlNode v, ResourceProvider? resourceProvider) {
    if (v is! YamlList) {
      return null;
    }
    YamlList nodeList = v;
  
    return _PSNodeList(_PSNode(key, resourceProvider),
        nodeList.nodes.map((n) => _PSNode(n, resourceProvider)));
  }
  
  PSEntry? _processScalar(
      YamlScalar key, YamlNode value, ResourceProvider? resourceProvider) {
    if (value is! YamlScalar) {
  
negative.code:           author = _processScalar(key, v, resourceProvider);
            break;
          case 'authors':
            authors = _processScalarList(key, v, resourceProvider);
            break;
          case 'homepage':
            homepage = _processScalar(key, v, resourceProvider);
  