chore: add test case for #14853

Author: paoloricciuti

packages/svelte/tests/runtime-runes/samples/inspect-trace-null/_config.js

@@ -0,0 +1,8 @@
+import { test } from '../../test';
+
+export default test({
+	compileOptions: {
+		dev: true
+	},
+	test() {}
+});

packages/svelte/tests/runtime-runes/samples/inspect-trace-null/main.svelte

@@ -0,0 +1,9 @@
+<script>
+	let count = $state(null);
+	$effect(() => {
+		$inspect.trace();
+		count;
+	});
+</script>
+
+<button onclick={()=>count++}>{count}</button>