vue-docgen-api: PropType<T> crashes if not used in prop.type field

[Disorrder]

Discovered this bug when used vue-intellisense which uses vue-docgen-api

Current behavior

It crashes with error

TypeError: Cannot read properties of undefined (reading 'length')
    at NodePath.each (/Users/disorder/Projects/PP/uikit/node_modules/recast/node_modules/ast-types/lib/path.js:72:30)
    at NodePath.filter (/Users/disorder/Projects/PP/uikit/node_modules/recast/node_modules/ast-types/lib/path.js:100:14)
    at /Users/disorder/Projects/PP/uikit/node_modules/vue-docgen-api/dist/script-handlers/propHandler.js:161:50
    at step (/Users/disorder/Projects/PP/uikit/node_modules/vue-docgen-api/dist/script-handlers/propHandler.js:52:23)
    at Object.next (/Users/disorder/Projects/PP/uikit/node_modules/vue-docgen-api/dist/script-handlers/propHandler.js:33:53)
    at /Users/disorder/Projects/PP/uikit/node_modules/vue-docgen-api/dist/script-handlers/propHandler.js:27:71
    at new Promise (<anonymous>)
    at __awaiter (/Users/disorder/Projects/PP/uikit/node_modules/vue-docgen-api/dist/script-handlers/propHandler.js:23:12)
    at /Users/disorder/Projects/PP/uikit/node_modules/vue-docgen-api/dist/script-handlers/propHandler.js:107:99
    at Array.map (<anonymous>)

To reproduce

import { defineComponent, PropType } from 'vue';

type PPIconType = 'name1' | 'name2';

export default defineComponent({
  name: 'test',

  props: {
    icon: String as PropType<PPIconType>, // <--- This is valid Vue syntax, but docgen is not working
    // icon: {
    //   type: String as PropType<PPIconType>, // <--- This is OK
    // },
  }
})

Expected behavior

It should not crash obviously and work like you wrapped type in object