你这个写法怎么说呢，感觉起来有点怪，button 下的那个 index.ts 里面，为什么是拿组件去 install app 呢，应该是 app 来 component 组件吧，尝试一下这个
button/index.ts

import MyButton from './index.vue'
import { App } from 'vue'

MyButton.name = 'MyButton'

MyButton.install = (app: App) => {
  app.component(MyButton.name, MyButton)
}

export default MyButton

packages/index.ts

import MyButton from './button'
import { App } from 'vue'

const components = [MyButton]
const install = (app: App) => {
  components.map(item => {
    app.component(item.name, item)
  })
}

export default install