Functions using reactive variables are hoisted outside of the instance

[EmilTholin]

The following piece of code throws VM47:312 Uncaught ReferenceError: square is not defined when clicking the button (REPL).

<script>
  let num = 2;
  $: square = num * num;
	
  function onClick() {
    console.log(square);
  }
</script>

<button on:click={onClick}>Click me</button>

It looks like the onClick function is being hoisted outside the instance function even though it uses square.

function onClick() {
  console.log(square);
}

function instance($$self, $$props, $$invalidate) {
  let square;

  $$self.$$.update = ($$dirty = { num: 1 }) => {
    if ($$dirty.num) {
      $$invalidate("square", (square = num * num));
    }
  };

  return {};
}

If I write let square; before the reactive statement it works as expected.