anchor.diff:    /**
      * constructs a GitObject of the given type.
      */
  -  static GitObject make(String sha, String type, String content) {
  +  static GitObject make(String sha, String type, content) {
       switch (type) {
         case ObjectTypes.BLOB:
           return new BlobObject(sha, content);
         case ObjectTypes.TREE:
  +      case "Tree":
           return new TreeObject(sha, content);
         case ObjectTypes.COMMIT:
           return new CommitObject(sha, content);
         case ObjectTypes.TAG:
           return new TagObject(sha, content);
         default:
  -        throw new ArgumentError("Unsupported git object type.");
  +        throw new ArgumentError("Unsupported git object type: ${type}");
       }
     }
   
  
positive.code:     this._type = parts[0];
      this._size = int.parse(parts[1]);
    }
  }
  
negative.code: 
    List<TreeEntry> entries;
  
    TreeObject(String sha, Uint8List data) {
      this._type = ObjectTypes.TREE;
      this._sha = sha;
      this.data = data;
  