NullPointerException raised by initialised ArrayList

Question

I ran the following program Duke and passed in the command 'todo apple'.

This is the error that I got:

Upon clicking line 23, I was directed to the following:

I have tried searching on NullPointerException but I am unsure of where I have gone wrong - would appreciate it if someone could point out :)

I have bolded the error lines in the code:

Duke.java

private Ui ui;
    private Storage storage;
    private TaskList taskList;
    private static Parser parser;

    public Duke(){
        ui = new Ui();
        taskList = new TaskList();
        storage = new Storage();
        parser = new Parser(ui, taskList, storage);
    }


    public static void main(String[] args) throws FileNotFoundException, DukeException {
        System.out.println("Hello! I'm Duke");
        System.out.println("What can I do for you?");

        PrintWriter writer = new PrintWriter("data/duke.txt");
        writer.print("");
        writer.close();

        Scanner sc = new Scanner(System.in);
        String cmd = sc.nextLine();

        boolean dukeExecuting = true;
        do{
            **dukeExecuting = parser.handleCommand(cmd);**
            if(cmd.equals("bye")){
                return;
            }
            cmd = sc.nextLine();
        }while(dukeExecuting);

    }
}

Parser.java

public class Parser {

    private static TaskList taskList;
    private static Ui ui;
    private static Storage storage;


    public Parser(Ui ui, TaskList taskList, Storage storage){
        this.ui = ui;
        this.taskList = taskList;
        this.storage = storage;

    }
    //adder functions
    private static void addTodo(String description) {
        **taskList.addTask(new Todo(description));**
        ui.printTodo(taskList);
    }

    private static void addDeadline(String description, String by) {
        taskList.addTask(new Deadline(description, by));
        ui.printDeadlineOrEvent(taskList);
    }

    private static void addEvent(String description, String by) {
        taskList.addTask(new Events(description, by));
        ui.printDeadlineOrEvent(taskList);
    }

    //handler functions
    private static void handleDone(String args){
        int index;
        //Check correct formatting
        try{
            index = Integer.parseInt(args);
        }catch(NumberFormatException e){
            System.out.println("Check formatting of usage of done!");
            return;
        }
        //Marking task as done
        try{
            ui.printDone(taskList, index);
        }catch(IndexOutOfBoundsException e){
            System.out.println("Task does not exist, please check again!");
        }
    }

    private static void handleTodo(String args){
        **addTodo(args);**
        ui.TaskAddedNotifier(taskList);
    }

    private static void handleDeadline(String desc, String by){
        addDeadline(desc,by);
        ui.TaskAddedNotifier(taskList);
    }

    private static void handleEvent(String desc, String by){
        addEvent(desc,by);
        ui.TaskAddedNotifier(taskList);
    }

    private static void handleDelete(String args){
        int index = Integer.parseInt(args);
        ui.printDelete(taskList, index);
    }

    private static void handleBye(){
        storage.saveList(taskList);
        System.out.println("Bye. Hope to see you again soon!");
    }


    public static boolean handleCommand(String cmd) throws DukeException {
        String cmdArgs = "";
        String cmdAfterSlash = "";
        int spaceIndex = cmd.indexOf(" ");
        int slashIndex = cmd.indexOf("/");
        //indexing
        if(spaceIndex != -1){
            cmdArgs = cmd.substring(spaceIndex+1).trim();
        }
        if(slashIndex != -1){
            cmdAfterSlash = cmd.substring(slashIndex+1).trim();
        }
        //cases
        if(cmd.startsWith("done")){
            handleDone(cmdArgs);
        }else if(cmd.startsWith("todo")){
            **handleTodo(cmdArgs);**
        }else if(cmd.startsWith("deadline")){
            handleDeadline(cmd.substring(spaceIndex+1,slashIndex), cmdAfterSlash);
        }else if(cmd.startsWith("event")) {
            handleEvent(cmd.substring(spaceIndex+1,slashIndex),cmdAfterSlash);
        }else if(cmd.equals("list")){
            ui.printTodoEventDeadlineList(taskList);
        }else if(cmd.startsWith("delete")){
            handleDelete(cmdArgs);
        }else if(cmd.equals("bye")){
            handleBye();
            return false;
        }else{
            throw new DukeException("☹ OOPS!!! I'm sorry, but I don't know what that means :-(");
        }
        return true;
    }
}

TaskList.java

import java.util.ArrayList;

public class TaskList {

    private static ArrayList<Task> tasks;

    public TaskList(){
        tasks = new ArrayList<Task>();
    }

    public ArrayList<Task> getTasks(){
        return tasks;
    }

    public int size(){
        return tasks.size();
    }

    public int tasksCount(){
        return tasks.size()-1;
    }

    public Task getTask(int index){
        return tasks.get(index);
    }

    public void addTask(Task task){
        tasks.add(task);
    }

    public void removeTask(int index){
        tasks.remove(index);
    }



}