[fix] correctly use paths.base to import assets (#6769)

Author: ota-meshi

.changeset/modern-books-confess.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+[fix] error when using `paths.base` and `import` assets

packages/kit/src/exports/vite/build/utils.js

@@ -147,7 +147,7 @@ export function get_default_build_config({ config, input, ssr, outDir }) {
  * @returns {string}
  */
 export function assets_base(config) {
-	return config.paths.assets + '/' || config.paths.base + '/' || './';
+	return (config.paths.assets || config.paths.base || '.') + '/';
 }
 
 const method_names = new Set(['GET', 'HEAD', 'PUT', 'POST', 'DELETE', 'PATCH']);

packages/kit/test/prerendering/paths-base/src/routes/assets/+page.svelte

@@ -0,0 +1,5 @@
+<script>
+	import logo from './logo.svg';
+</script>
+
+<img src={logo} alt="Svelte logo" />

packages/kit/test/prerendering/paths-base/src/routes/assets/logo.svg

@@ -18,4 +18,9 @@ test('prerenders /path-base/dynamic/foo', () => {
 	assert.ok(content.includes('<h1>foo</h1>'));
 });
 
+test('prerenders /path-base/assets', () => {
+	const content = read('assets.html');
+	assert.match(content, /<img[^>]+src="\/path-base\//u);
+});
+
 test.run();