Есть ли в коде ошибки?

StringBuffer line = new StringBuffer();
            while (reader.ready())
                line.append(reader.readLine());
            Pattern pattern = Pattern.compile("args[0]" + ".*?>");
            Matcher matcher = pattern.matcher(line);
            ArrayList<Tag> tags = new ArrayList<>();
            while (matcher.find()) {
                if (!line.substring(matcher.start() - 1, matcher.start()).equals("/"))
                    tags.add(new Tag(matcher.start()-1,matcher.end(),"open"));
                else tags.add(new Tag(matcher.start()-2,matcher.end(),"closed"));}
            ArrayList<String> inner = new ArrayList<>();
            boolean isNew = false;  int count = 0;  Tag firstTag = null;
            for(int i = 0; i < tags.size(); i++){
                if(!isNew){
                    firstTag = tags.get(i);
                    isNew = true;}
                if(tags.get(i).type.equals("open")){
                    count++;}
                else { count--;
                    if(count == 0){
                        System.out.println(line.substring(firstTag.first, tags.get(i).last));
                        tags.remove(tags.get(i));   tags.remove(firstTag);
                        i-=2;   isNew = false;
                        inner.forEach(System.out::println);
                        inner.clear();}
                    else{
                        inner.add(line.substring(tags.get(i-1).first,tags.get(i).last));
                        tags.remove(tags.get(i));   tags.remove(tags.get(i-1));
                        i-=2;}  }
            }
        }
    }
    public static class Tag {
        public int first;
        public int last;
        public String type;
        public Tag (int first, int last, String type){
            this.first = first;
            this.last = last;
            this.type = type;}
    }
}

public static void solution(String input, String tag) {
        String filteredInput = input.replaceAll("[\n\r]", "");
        String startTag = "<" + tag;
        String endTag = "</" + tag + ">";

        Stack<Integer> startIndexes = new Stack<>();
        Map<Integer, Integer> indexPairs = new TreeMap<>();

        StringBuilder builder = new StringBuilder();
        int currentTagStart = 0;
        boolean readingTag = false;
        for (int i = 0; i < filteredInput.length(); i++) {
            char currentChar = filteredInput.charAt(i);

            if (currentChar == '<') {
                readingTag = true;
                currentTagStart = i;
            }
            if (currentChar == '>') {
                readingTag = false;
                String tagString = builder.append(currentChar).toString();
                builder = new StringBuilder();

                if (tagString.startsWith(startTag)) {
                    startIndexes.push(currentTagStart);
                }

                if (tagString.equals(endTag)) {
                    Integer start = startIndexes.pop();
                    indexPairs.put(start, i + 1);
                }
            }
            if (readingTag) {
                builder.append(currentChar);
            }
        }

        indexPairs.forEach((key, value) -> System.out.println(filteredInput.substring(key, value)));
    }