@typescript-eslint/no-unnecessary-condition false positive when property is defined anywhere other than the last line of script tag

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<script>
    let foo = undefined
    1 // remove this line and the error goes away
</script>

<button on:click={() => (foo = 'asdf')}>asdf</button>
{#if foo !== undefined}
    <p>clicked</p>
{/if}

7:6  error  Unnecessary conditional, both sides of the expression are literal values  @typescript-eslint/no-unnecessary-condition

✖ 1 problem (1 error, 0 warnings)

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this issue doesn't occur in eslint-plugin-svelte which seems to be more actively maintained

• This plugin is deprecated in favor of eslint-plugin-svelte #184