Function cleanup

packages/next/src/server/lib/router-utils/proxy-request.ts:60–70

(err: any)

  proxy.on('proxyRes', (proxyRes, innerReq, innerRes) => {
    const cleanup = (err: any) => {
      // cleanup event listeners to allow clean garbage collection
      proxyRes.removeListener('error', cleanup)
      proxyRes.removeListener('close', cleanup)
      innerRes.removeListener('error', cleanup)
      innerRes.removeListener('close', cleanup)

      // destroy all source streams to propagate the caught event backward
      innerReq.destroy(err)
      proxyRes.destroy(err)
    }

    proxyRes.once('error', cleanup)
    proxyRes.once('close', cleanup)