chore: avoid update falsy node

[SoloJiang]

Replay code:

import { createElement, render, useState, Fragment } from 'rax';
import Driver from 'driver-universal';

let index = 0;

function Home() {
  const [arr, setArr] = useState([1, 2, 3, 4, 5, 6]);
  function click() {
    switch (index) {
      case 0:
        setArr([4, 5, 6]);
        break;
      case 1:
        setArr([1]);
        break;
      default:
        break;
    }
    index++;
  }
  return (
    <div onClick={click}>
      {new Array(6).fill(1).map((v, index) => (
        <Fragment key={index}>{arr[index]}</Fragment>
      ))}
    </div>
  );
}
render(<Home />, document.getElementById('root'), { driver: Driver });

More simple case, u can see the added test cases.

[CLAassistant]

All committers have signed the CLA.