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Improper webpack `devtool` used in development mode

Why This Error Occurred​

Next.js chooses the most optimal devtool for use with webpack. Changing the devtool in development mode will cause severe performance regressions with your application.

Possible Ways to Fix It​

Please remove the custom devtool override or only apply it to production builds in your next.config.js.

module.exports = {
  webpack: (config, options) => {
    if (!options.dev) {
      config.devtool = options.isServer ? false : 'your-custom-devtool'
    }
    return config
  },
}