Change `utils` because TS does not take account the field.

package.json

@@ -93,6 +93,6 @@
     "./dist/js/*": "./dist/js/*",
     "./dist/css/*": "./dist/css/*",
     "./dist/css/themes/*": "./dist/css/themes/*",
-    "./utils": "./src/js/utils/index.ts"
+    "./src/js/utils": "./src/js/utils/index.ts"
   }
 }