Svelte bug report: Array assignment reactivity not working; adding a line-end comment bizarrely fixes it

+page.svelte

<script>
    // copy this script to https://svelte.dev/repl/
    // (github login on svelte.dev is not working for me, so I cannot save on the REPL)
    export let propdata = [1, 1]
    console.log("initial propdata", propdata)
    $: editedData = [...propdata]
    
    function add() {
        console.log("clicked")
        editedData.push(1)
	console.log("element added, editedData set to (no reactivity)", editedData)
        console.log("triggering reactivity on editedData", editedData)
        editedData = editedData
    }

    $: console.log("$: propdata set to", propdata)
    $: console.log("$: editedData set to", editedData)
</script>
<button on:click={add}>Add</button>
{JSON.stringify(editedData)}
<p><tt>propdata</tt> is incorrectly invalidated on line 13 when editedData is invalidated, breaking the Add button.</p>
<p>Bizarrely, this is fixed if you add any line-end comment to line 13, e.g. <tt>editedData = editedData // this works</tt></p>
<p>If you add a semicolon AND a comment, it does not work, so the following is still broken: <tt>editedData = editedData; // this doesn't work</tt></p>
<p>The JS output for add() without the comment is:</p>
<pre>{`
function add() {
	console.log("clicked");
	editedData.push(1);
	console.log("element added, editedData set to (no reactivity)", editedData);
	console.log("triggering reactivity on editedData", editedData);
	($$invalidate(0, editedData), $$invalidate(2, propdata));
}`}
</pre>
<p>We see that <tt>propdata</tt> is incorrectly invalidated alongside <tt>editedData</tt>.</p>
<p>The JS output for add() <strong>with</strong> the comment (working correctly) is:</p>
<pre>{`
function add() {
	console.log("clicked");
	editedData.push(1);
	console.log("element added, editedData set to (no reactivity)", editedData);
	console.log("triggering reactivity on editedData", editedData);
	$$invalidate(0, editedData = editedData); //
}`}
</pre>
<p>Only <tt>editedData</tt> is invalidated.</p>
<!--
Console output after clicking Add twice, showing Add button does not update editedData:

"initial propdata" (2) [ 1 ,1 ]
"$: propdata set to" (2) [ 1 ,1 ]
"$: editedData set to" (2) [ 1 ,1 ]
"clicked"
"element added, editedData set to (no reactivity)" (3) [ 1 ,1 ,1 ]
"triggering reactivity on editedData" (3) [ 1 ,1 ,1 ]
"$: propdata set to" (2) [ 1 ,1 ]
"$: editedData set to" (2) [ 1 ,1 ]
"clicked"
"element added, editedData set to (no reactivity)" (3) [ 1 ,1 ,1 ]
"triggering reactivity on editedData" (3) [ 1 ,1 ,1 ]
"$: propdata set to" (2) [ 1 ,1 ]
"$: editedData set to" (2) [ 1 ,1 ]
-->