prepareWebpackConfig () {
    this.clientConfig = createClientConfig(this.context).toConfig()
    this.serverConfig = createServerConfig(this.context).toConfig()

    const userConfig = this.context.siteConfig.configureWebpack
    if (userConfig) {
      this.clientConfig = applyUserWebpackConfig(userConfig, this.clientConfig, false)
      this.serverConfig = applyUserWebpackConfig(userConfig, this.serverConfig, true)
    }
  }
Prepare webpack config under build.

@api private