fix: reduce warning log to single line and ignore in testcase

Author: dominikg

packages/e2e-tests/scan-deps/__tests__/scan-deps.spec.ts

@@ -3,7 +3,9 @@ import { describe, expect, it } from 'vitest';
 describe('vite import scan', () => {
 	it('should not fail to discover dependencies exported from script module', async () => {
 		// vite logs an error if scan fails but continues, so validate no errors logged
-		const errorLogs = e2eServer.logs.server.err;
+		const errorLogs = e2eServer.logs.server.err.filter(
+			(line) => !line.includes('Support for rolldown-vite in vite-plugin-svelte is experimental')
+		);
 		expect(errorLogs.length, `unexpected errors:\n${errorLogs.join('\n')}`).toBe(0);
 	});
 	it('should work with exports from module context', async () => {

packages/vite-plugin-svelte/src/index.js

@@ -39,10 +39,9 @@ export function svelte(inlineOptions) {
 		log.setLevel('debug');
 	}
 	if (rolldownVersion) {
-		log.warn.once('!!! Support for rolldown-vite in vite-plugin-svelte is experimental !!!', {
-			rolldownVersion,
-			viteVersion
-		});
+		log.warn.once(
+			`!!! Support for rolldown-vite in vite-plugin-svelte is experimental (rolldown: ${rolldownVersion}, vite: ${viteVersion}) !!!`
+		);
 	}
 
 	validateInlineOptions(inlineOptions);