Error in callback for watcher "echartData": "TypeError: Cannot read properties of undefined (reading 'length')"

以下是关于"Error in callback for watcher 'echartData': 'TypeError: Cannot read properties of undefined (reading 'length')'"的解释和演示：
1. 对象属性检查

var b = {name:1}
console.log(b.hasOwnProperty('name')) // 输出：true

2. Promise执行顺序

const p1 = new Promise((resolve, reject) => {
  setTimeout(() => {
    resolve(1)
    throw new Error('p1失败信息')
  }, 2000)
})

const p2 = p1
  .then((val) => {
    console.log(val, 'p2成功返回的')
    return val + 1
  })
  .catch((err) => {
    console.log(err, 'p2失败返回的')
    return err
  })

Promise.all([p2, Promise.reject(3)])
  .then((val2) => {
    console.log(val2, 'all成功返回的')
  })
  .catch((err2) => {
    console.log(err2, 'all失败返回的')
})