eslint-plugin-svelte false positive (sveltejs/eslint-plugin-svelte#335)

.eslintrc.json

{
  "parser": "svelte-eslint-parser",
  "parserOptions": {
    "parser": "@typescript-eslint/parser",
    "extraFileExtensions": [".svelte"]
  },
  "rules": {
    "no-undef": "error"
  }
}

Error.svelte

<script lang="ts">
  const contentPromise = new Promise();
</script>

{#if false}
{:else if true}
  {#await contentPromise then _}
  {/await}
{/if}

package.json

{
  "scripts": {
    "lint": "eslint --color 'Error.svelte'"
  },
  "dependencies": {
    "@typescript-eslint/parser": "^5.36.1",
    "eslint": "^8.23.0",
    "eslint-plugin-svelte": "^2.8.0",
    "svelte": "^3.50.0"
  }
}