What's wrong with my code? It compiles and works fine in IDE

package com.teamtreehouse.courses;

import com.teamtreehouse.courses.model.CourseIdea;
import com.teamtreehouse.courses.model.CourseIdeaDAO;
import com.teamtreehouse.courses.model.SimpleCourseIdeaDAO;
import spark.ModelAndView;
import spark.template.handlebars.HandlebarsTemplateEngine;

import java.util.HashMap;
import java.util.Map;

import static spark.Spark.*;

/**
 * Created by nfleig on 16.07.17.
 */
public class Main {
    public static void main(String[] args) {
        staticFileLocation("/public");
        CourseIdeaDAO dao = new SimpleCourseIdeaDAO(); //This SimpleCourseIeaDAO is not meant for production. Just a prototype. Should be linked to a DB

        get("/", (req, res) -> {
            Map<String, String> model = new HashMap<>();
            model.put("username", req.cookie("username"));
            return new ModelAndView(model, "index.hbs");
        }, new HandlebarsTemplateEngine());

        // Replaces previous post request. This one redirects to main page.
        post("/", (req, res) -> {
           String username = req.queryParams("username");
           res.cookie("username", username);
           res.redirect("/");
           return null;
        });

        get("/ideas", (req, res) -> {
            Map<String, Object> model = new HashMap<>();
            model.put("ideas", dao.findAll());
            return new ModelAndView(model, "ideas.hbs");
        }, new HandlebarsTemplateEngine());

        post("/ideas", (req, res) -> {
           String title = req.queryParams("title");

           //TODO:nfa - This username is tied to the cookie. Problem: only way to know user is logged in is by cookie
           CourseIdea courseIdea = new CourseIdea(title,
                    req.cookie("username"));
           dao.add(courseIdea);
           res.redirect("/ideas");
           return null;
        });
    }
}