Is there anything missing to use Chart.js on a Svelte app?

I am new to Svelte and having trouble displaying a graph using Chart.js on a SvelteKit page.

First, I tried to put a canvas and confirmed that it worked, as the code below shows a black canvas on a page if you comment out the onMount function. However, it doesn't show anything after adding the onMount part. There is no error indication in the browser and terminal console, so I am stuck with it.

I use the latest version of Sveltekit and Chart.js. Is there anything missing?

<script>
    import { onMount } from 'svelte';
    import Chart from 'chart.js/auto';

    let data = [20, 100, 50, 12, 20, 130, 45];
    let labels = ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday', 'Sunday'];
    let ctx;
    let canvas;

    onMount(() => {
        ctx = canvas.getContext('2d');
        var chart = new Chart(ctx, {
            type: 'bar',
            data: {
                labels: labels,
                datasets: [
                    {
                        label: 'Unit Sales',
                        data: data
                    }
                ]
            }
        });
    });
</script>

<canvas bind:this={canvas} width={32} height={32} />

<style>
    canvas {
        width: 100%;
        height: 100%;
        background-color: #666;
    }
</style>