Meal Maker

hello fellow programmers. I’ve been stuck on this task for about an hour now and I’m close to the end, but I encounter another problem. I checked the code and can’t find the mistake. when I add
menu.addDishToCourse(‘appetizers’, ‘Caesar Salad’, 4.25);
it puts this syntaxerror:

const menu = {
_courses : {
appetizers: ,
mains: ,
desserts: ,
},

get appetizers() {

/home/ccuser/workspace/learn-javascript-objects-meal-maker/app.js:11
return this._course.appetizers
^

TypeError: Cannot read property ‘appetizers’ of undefined
at Object.get appetizers [as appetizers] (/home/ccuser/workspace/learn-javascript-objects-meal-maker/app.js:11:20)
at Object.get _courses [as _courses] (/home/ccuser/workspace/learn-javascript-objects-meal-maker/app.js:40:21)
at Object.addDishToCourse (/home/ccuser/workspace/learn-javascript-objects-meal-maker/app.js:52:5)
at Object. (/home/ccuser/workspace/learn-javascript-objects-meal-maker/app.js:71:6)
at Module._compile (module.js:571:32)
at Object.Module._extensions…js (module.js:580:10)
at Module.load (module.js:488:32)
at tryModuleLoad (module.js:447:12)
at Function.Module._load (module.js:439:3)
at Module.runMain (module.js:605:10)

For further info, here’s my code
const menu = {
_courses : {
appetizers: ,
mains: ,
desserts: ,
},

get appetizers() {
return this._course.appetizers
},

set appetizers(appetizers) {
this._courses.appetizers = appetizers
},

get mains() {
return this._courses.mains
},

set mains(mains) {
this._courses.mains = mains
},

get desserts() {
return this._courses.desserts
},

set desserts(desserts) {
this._courses.desserts = desserts
},

get _courses() {
return {
appetizers: this.appetizers,
mains: this.mains,
desserts: this.desserts
}
},
addDishToCourse (courseName, dishName, totalPrice) {
const dish = {
name : dishName,
price : totalPrice
};

this._courses[courseName].push(dish);
},
getRandomDishFromCourse(courseName) {
const dishes = this._courses[courseName];
const randomIndex = Math.floor(Math.random() * dishes.length);
},

 generateRandomMeal: function() {
const appetizer = this.getRandomDishFromCourse('appetizers');
const main = this.getRandomDishFromCourse('mains');
const dessert = this.getRandomDishFromCourse('desserts');

const totalPrice = appetizer.price + main.price + dessert.price;

return `Your meal is ${appetizer.name} ${main.name}, and The price is ${totalPrice}.`;

},
};