function withDefaults(props, defaults) {
      {
          warnRuntimeUsage(`withDefaults`);
      }
      return null;
  }
Vue `<script setup>` compiler macro for providing props default values when
using type-based `defineProps` declaration.

Example usage:
```ts
withDefaults(defineProps<{
  size?: number
  labels?: string[]
}>(), {
  size: 3,
  labels: () => ['default label']
})
```

This is only usable inside `<script setup>`, is compiled away in the output
and should **not** be actually called at runtime.