Fix order of main fields

vitest.base.unit.config.ts

@@ -6,7 +6,7 @@ export default defineConfig({
   resolve: {
     // Adding `deno` field is just for testing purpose.
     // Vite validates the package.json and could not find `lib/index.js` in deno runtime
-    mainFields: ["deno", "main"],
+    mainFields: ["browser", "module", "jsnext:main", "jsnext", "deno", "main"],
   },
   test: {
     include: ["**/*.test.ts"],