No TypeScript error overlay in development after updating to 9.4

Bug report

I updated nextjs from 9.3.6 to 9.4.0.

Describe the bug

After updating I do not get typescript errors anymore checked during buildtime. This was working in 9.3.6.

To Reproduce

As I have quite a complex mono repository, I’m unable to provide the source of that. Major differences to a stock configuration is a custom babel configuration:

module.exports = {
  presets: [],
  plugins: [
    'lodash',
    '@babel/proposal-class-properties',
    'react-intl-auto',
    'babel-plugin-graphql-tag'
  ],
  env: {
    test: {
     presets: [
       '@babel/typescript',
         [ '@babel/preset-env',
           {
           targets: {
             node: process.versions.node
           }
         }
         ],
       '@babel/preset-react'
     ]
    },
    nodeTs: {
      presets: [
        '@babel/typescript',
        '@babel/preset-react',
        [
          '@babel/preset-env',
          {
            targets: {
              node: process.versions.node
            }
          }
        ]
      ]
    },
    nextjs: {
      presets: ['next/babel']
    }
  }
}

And a custom next.config.ts:

/* eslint-disable @typescript-eslint/no-var-requires */
const path = require('path')

const withDevTool = (nextConfig: any = {}) => {
  return {
    ...nextConfig,
    webpack(config: any, options: any) {
      const { dev } = options
      if (dev) {
        config.devtool = 'eval-source-map'
      }
      if (typeof nextConfig.webpack === 'function') {
        return nextConfig.webpack(config, options)
      }
      return config
    },
  }
}

export default () => {
  const optimizedImages = require('next-optimized-images')

  const withTM = require('next-transpile-modules')([
    'query-string',
    'imask/esm',
   /** ..some more private modules */
  ])

  const withCustomBabelConfigFile = require('next-plugin-custom-babel-config')
  const withCSS = require('@zeit/next-css')

  const withBundleAnalyzer = require('@next/bundle-analyzer')({
    enabled: process.env.ANALYZE === 'true',
  })

  return withDevTool(
    withBundleAnalyzer(
      optimizedImages(
        withCustomBabelConfigFile(
          withCSS(
            withTM({
              babelConfigFile: path.resolve(
                path.join(__dirname, '../../../../babel.config.js')
              ),
              distDir: 'dist',
            })
          )
        )
      )
    )
  )
}

I’m using a custom server with additional express middleware.

// This file doesn't go through babel or webpack transformation.
// Make sure the syntax and sources this file requires are compatible with the current node version you are running
// See https://github.com/zeit/next.js/issues/1245 for discussions on Universal Webpack or universal Babel
import 'dotenv/config'
import express from 'express'
import next from 'next'
import { defaultMiddleware } from '../index'
import { appConfig } from './appConfig'

const applicationFactory = (): void => {
  const dev = process.env.NODE_ENV !== 'production'
  const conf = dev
    ? // eslint-disable-next-line @typescript-eslint/no-var-requires
      require('./next.config').default()
    : {
        distDir: 'dist',
      }
  const app = next({
    dev,
    conf,
  })
  const handle = app.getRequestHandler()
  app.prepare().then(() => {
    const server = express()
    const proxyInstance = defaultMiddleware(server, appConfig)
    server.get('*', (req, res) => {
      return handle(req, res)
    })
    const port = process.env.PORT || 3000
    // @ts-ignore
    const listener = server.listen(port, (err: Error) => {
      if (err) {
        throw err
      }
      // tslint:disable-next-line:no-console
      console.log(`> Ready on http://localhost:${port}`)
    })
    listener.on('upgrade', (req: any, socket: any, ...rest: any) => {
      socket.on('error', (error: any) => {
        console.error(error)
      })
      proxyInstance.upgrade(req, socket, ...rest)
    })
  })
}

export default applicationFactory

Expected behavior

Typescript errors should be reported.

System information

• OS: Windows
• Version of Next.js: 9.4.0
• Version of Node.js: 12.13.1

[vitrukroman]

Please add an option to enable typescript checks for the whole code during development

[Timer]

Hello! This is intended as part of the new Fast Refresh experience. We wanted to make updates visible as fast as possible, without interrupting your train of thought for a type error.

We feel type checking in development is better done passively by your editor!

Plus, we can recover from runtime errors now so it’s not necessary to pass type checking to test your application (a runtime error won’t cause you to lose application state).

Type checking is still performed during your production build.