BFF Plugin error: Cannot remove headers after they are sent to the client

[FelipeMenezesDM]

Every time I access the route I created in /api/lambda/token.ts, this error appears and the server shuts down:

access url: /api/token
error   Error: Cannot remove headers after they are sent to the client
    at ServerResponse.removeHeader (node:_http_outgoing:848:11)
    at write (...\node_modules\finalhandler\index.js:287:9)
    at AsyncResource.runInAsyncScope (node:async_hooks:211:14)
    at listener (...\node_modules\on-finished\index.js:170:15)
    at onFinish (...\node_modules\on-finished\index.js:101:5)
    at callback (...\node_modules\ee-first\index.js:55:10)
    at IncomingMessage.onevent (...\node_modules\ee-first\index.js:93:5)
    at IncomingMessage.emit (node:events:524:28)
    at IncomingMessage.emit (node:domain:489:12)
    at endReadableNT (node:internal/streams/readable:1698:12)
    at processTicksAndRejections (node:internal/process/task_queues:90:21)

Current settings:

import { appTools, defineConfig } from '@modern-js/app-tools';
import bffPlugin from '@modern-js/plugin-bff/cli';
import expressPlugin from '@modern-js/plugin-express';

// https://modernjs.dev/en/configure/app/usage
export default defineConfig({
  dev: {
    port: 3005,
  },
  runtime: {
    router: true,
    state: true,
  },
  server: {
    ssr: true
  },
  plugins: [
    appTools({
      bundler: 'rspack',
    }),
    expressPlugin(),
    bffPlugin(),
  ],
});

In the token.ts file, there is this test code:
export const get = async () => 'Hello Modern.js';