select_change_handler fails with exposed slot property

[caleeli]

Describe the bug

When a <select> component contains a <CustomComponent let:options>, when the user select an option, the following exception is thrown:

options is not defined
HTMLSelectElement.select_change_handler
[https://bhx905.csb.app/App.svelte:323:21]()

Reproduction

https://codesandbox.io/s/practical-hooks-bhx905?file=/App.svelte

Main component

<script>
  import RemoteOptions from "./RemoteOptions.svelte";
  let value = "";
  // workaround
  // let options = [];
</script>

<main>
  <select bind:value={value}>
    <option></option>
    <RemoteOptions let:options={options}>
      {#each options as option}
        <option value={option.value}>{option.label}</option>
      {/each}
    </RemoteOptions>
  </select>
  value={value}
</main>

RemoteOptions component

<script>
	let endpoint = new Promise(resolve => {
	  resolve([
	    {
	      value: "1",
	      label: "one"
	    },
	    {
	      value: "2",
	      label: "two"
	    }
	  ]);
	});
</script>

{#await endpoint}
	<slot options={[]} />
{:then options}
	<slot {options} />
{/await}

Logs

options is not defined
HTMLSelectElement.select_change_handler
[https://bhx905.csb.app/App.svelte:323:21]()

Doing some debug, the following code is generated:

  let value = "";
  const writable_props = [];
  Object.keys($$props).forEach(key => {
    if (!~writable_props.indexOf(key) && key.slice(0, 2) !== "$$") console.warn(`<App> was created with unknown prop '${key}'`);
  });

  function select_change_handler() {
    value = (0, _internal.select_value)(this);
    $$invalidate(0, value);
    $$invalidate(2, options);
  }

Note: options is not defined, since it is the property exposed by the <RemoteOptions> component

### System Info

```shell
System:
    OS: Linux 5.8 Ubuntu 20.10 (Groovy Gorilla)
    CPU: (8) x64 Intel(R) Core(TM) i5-1035G7 CPU @ 1.20GHz
    Memory: 672.45 MB / 15.39 GB
    Container: Yes
    Shell: 5.0.17 - /bin/bash
  Binaries:
    Node: 14.4.0 - ~/.config/nvm/versions/node/v14.4.0/bin/node
    Yarn: 1.22.11 - ~/.config/nvm/versions/node/v14.4.0/bin/yarn
    npm: 6.14.5 - ~/.config/nvm/versions/node/v14.4.0/bin/npm
  Browsers:
    Brave Browser: 87.1.18.75
    Chrome: 99.0.4844.51
    Firefox: 90.0
  npmPackages:
    rollup: ^2.3.4 => 2.56.2 
    svelte: ^3.46.4 => 3.46.4

Severity

annoyance

[gtm-nayan]

fixed by #8969