refs in deep watch not working

[webfansplz]

Version: 1.0.0-rc.13

The reproduced demo is: https://codesandbox.io/s/sharp-lamarr-04z91

The main code is as follows:

<script>


import { watch, ref, computed, reactive } from "@vue/composition-api";

export default {
  name: "App",
  components: {
    HelloWorld,
  },
  setup() {
    const count = ref(0);
    const double = computed(() => count.value * 2);
    const state = reactive([count, double]);

    let dummy;
    watch(
      () => state,
      (state) => {
        dummy = [state[0].value, state[1].value];
      },
      { deep: true }
    );

    count.value++;
    console.log(dummy); // // output undefined.
  },
};
</script>