vp check fails JS functions cannot be represented as a serde_json::Value

[shyim]

Describe the bug

❯ vp check 
VITE+ - The Unified Toolchain for the Web

error: Formatting could not start
Failed to load configuration file.
/Users/shyim/Developer/shopmon/frontend/vite.config.mjs
Error: JS functions cannot be represented as a serde_json::Value
Ensure the file has a valid default export of a JSON-serializable configuration object.

Formatting failed before analysis started

My vite.config.mjs

import { URL, fileURLToPath } from "node:url";

import tailwindcss from "@tailwindcss/vite";
import Vue from "@vitejs/plugin-vue";
import IconsResolver from "unplugin-icons/resolver";
import Icons from "unplugin-icons/vite";
import Components from "unplugin-vue-components/vite";
import { defineConfig } from "vite-plus";

const hmr = {};

if (process.env.HMR_PORT) {
  hmr.clientPort = process.env.HMR_PORT;
}

export default defineConfig({
  fmt: {},
  plugins: [
    tailwindcss(),
    Vue(),
    Components({
      resolvers: [
        IconsResolver({
          prefix: "icon",
        }),
      ],
    }),
    Icons({
      autoInstall: true,
      scale: 1,
    }),
  ],
  resolve: {
    alias: {
      "@": fileURLToPath(new URL("./src", import.meta.url)),
    },
  },
  server: {
    hmr,
    proxy: {
      "/api": {
        target: process.env.SHOPMON_API_URL || "https://shopmon.fos.gg",
        changeOrigin: true,
      },
    },
  },
});

When I uncomment all plugins it works.

Reproduction

x

Steps to reproduce

No response

System Info

ITE+ - The Unified Toolchain for the Web

Environment:
  Version  24.14.1
  Source   lts

Tool Paths:
  node  /Users/shyim/.vite-plus/js_runtime/node/24.14.1/bin/node
  npm   /Users/shyim/.vite-plus/js_runtime/node/24.14.1/bin/npm
  npx   /Users/shyim/.vite-plus/js_runtime/node/24.14.1/bin/npx



VITE+ - The Unified Toolchain for the Web

vp v0.1.15

Local vite-plus:
  vite-plus  v0.1.15

Tools:
  vite             v8.0.3
  rolldown         v1.0.0-rc.12
  vitest           v4.1.2
  oxfmt            v0.43.0
  oxlint           v1.58.0
  oxlint-tsgolint  v0.18.1
  tsdown           v0.21.7

Environment:
  Package manager  npm v11.12.1
  Node.js          v24.14.1

Used Package Manager

npm

Logs

Validations

• Read the Contributing Guidelines.
• Check that there isn't already an issue for the same bug.
• Confirm this is a Vite+ issue and not an upstream issue (Vite, Vitest, tsdown, Rolldown, or Oxc).
• The provided reproduction is a minimal reproducible example.