fix: correctly compile server code when using `$inspect` after a top-level await expression (#17407)

* add fix and test

* changeset

* Apply suggestion from @teemingc

.changeset/spicy-years-stick.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: remove `$inspect` calls after await expressions when compiling for production server code

packages/svelte/src/compiler/phases/3-transform/shared/transform-async.js

@@ -86,7 +86,14 @@ export function transform_body(instance_body, runner, transform) {
 			}
 
 			if (s.node.type === 'ExpressionStatement') {
-				const expression = /** @type {ESTree.Expression} */ (transform(s.node.expression));
+				// the expression may be a $inspect call, which will be transformed into an empty statement
+				const expression = /** @type {ESTree.Expression | ESTree.EmptyStatement} */ (
+					transform(s.node.expression)
+				);
+
+				if (expression.type === 'EmptyStatement') {
+					return null;
+				}
 
 				return expression.type === 'AwaitExpression'
 					? b.thunk(expression, true)

packages/svelte/tests/snapshot/samples/async-top-level-inspect-server/_config.js

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

packages/svelte/tests/snapshot/samples/async-top-level-inspect-server/_expected/client/index.svelte.js

@@ -0,0 +1,16 @@
+import 'svelte/internal/disclose-version';
+import 'svelte/internal/flags/async';
+import * as $ from 'svelte/internal/client';
+
+var root = $.from_html(`<p> </p>`);
+
+export default function Async_top_level_inspect_server($$anchor) {
+	var data;
+	var $$promises = $.run([async () => data = await Promise.resolve(42),,]);
+	var p = root();
+	var text = $.child(p, true);
+
+	$.reset(p);
+	$.template_effect(() => $.set_text(text, data), void 0, void 0, [$$promises[1]]);
+	$.append($$anchor, p);
+}

packages/svelte/tests/snapshot/samples/async-top-level-inspect-server/_expected/server/index.svelte.js

@@ -0,0 +1,15 @@
+import 'svelte/internal/flags/async';
+import * as $ from 'svelte/internal/server';
+
+export default function Async_top_level_inspect_server($$renderer) {
+	var data;
+	var $$promises = $$renderer.run([async () => data = await Promise.resolve(42),,]);
+
+	$$renderer.push(`<p>`);
+
+	$$renderer.async([$$promises[1]], ($$renderer) => {
+		$$renderer.push(() => $.escape(data));
+	});
+
+	$$renderer.push(`</p>`);
+}

packages/svelte/tests/snapshot/samples/async-top-level-inspect-server/index.svelte

@@ -0,0 +1,6 @@
+<script>
+	let data = await Promise.resolve(42);
+	$inspect(data);
+</script>
+
+<p>{data}</p>