Sveltestrap's modal header is not rendered correctly

i'm a svelte beginner.

I try to build a simple modal with Sveltestrap, but my modal is not rendered correctly. It always showing following text within modal instead of header:

(node, ...args) => { var previous_component_function = dev_current_component_function; set_dev_current_component_function(component2); try { return fn(node, ...args); } finally { set_dev_current_component_function(previous_component_function); } }

My Code looks like that:

<script lang="ts">    import { Modal, ModalFooter, Button } from "@sveltestrap/sveltestrap";    let {open = $bindable()}:{        open: boolean    } = $props();    const toggle = () => (open = !open);</script><Modal body header="Demo Modal" isOpen={open} {toggle}><ModalFooter><Button color="primary" on:click={toggle}>Hinzufügen</Button><Button color="secondary" on:click={toggle}>Abbrechen</Button></ModalFooter></Modal>

Any help would be appreciate.

regards