If Props'property is not "basic type" ,<withDefaults> will give undefined to them.

[Darma1106]

example :

<script setup lang="ts">
import { onMounted } from '@vue/composition-api';
type Test = number[];

interface Props{
    test: number[];
    test2: Test;
}
const props = withDefaults(defineProps<Props>(), {
    test:()=>[1, 2, 3],
    test2:()=>[1, 2, 3]
});

onMounted(()=>{
    console.log(props, 'props'); // => { test: [1,2,3] , test2:undefined }
});
</script>