Slot props produce `no-undef` error on <slot>

[janosh]

#109 was opened for <svelte:fragment>. The same problem occurs with <slot />:

    <Select
      options={actions}
      bind:input
      placeholder="Go to..."
      on:add={move}
      on:keydown={toggle}
    >
      <!-- wait for https://github.com/sveltejs/svelte/pull/8304 -->
      <slot slot="option" name="option" let:option>
        <span>{option.label}</span>
      </slot>
    </Select>