问贝宝RESTK400Error (node.js)有关验证错误的内容(错误写在描述中)

EN

name: 'VALIDATION_ERROR',
  details: [
    {
      field: 'purchase_units[0]',
      issue: 'Item amount must add up to specified amount subtotal (or total if amount details not specified)'
    }
  ],
  message: 'Invalid request - see details',
  information_link: 'https://developer.paypal.com/docs/api/payments/#errors',
  debug_id: '74ac8660674d8',
  httpStatusCode: 400

app.post('/pay' , (req , res) => {

    let cart = new Cart(req.session.cart)
    
    
    const create_payment_json = {
    "intent": "sale",
    "payer": {
        "payment_method": "paypal"
    },
    "redirect_urls": {
        "return_url": "http://localhost:3000/success",
        "cancel_url": "http://localhost:3000/failed"
    },
    "transactions": [{
        "item_list": {
            "items": getItems(cart.items)
        },
        "amount": {
            "currency": "USD",
            "total": cart.totalPrice
        },
        "description": "This is the payment description."
    }]
};

function getItems(cart) {
    let itemsArray = [];
    for (const [idx, item] of Object.entries(cart)) {
      itemsArray.push({
                "name": item.item.product_name, 
                "price": item.price,
                "currency": "USD",
                "quantity": item.qty
            });
    }
    return itemsArray;

}