[BUG] http-proxy-middleware@1.1.1 : "Cannot read property 'host' of undefined" if target not set and router returns unresolvable URL.

Is this a bug report?

YES

Steps to reproduce

• package.json :

{
  "name": "testbug",
  "version": "0.0.0",
  "dependencies": {
    "express": "4.17.1",
    "http-proxy-middleware": "1.1.1"
  }
}

• test.js

const express = require('express')

const app = express()

const { createProxyMiddleware  } = require('http-proxy-middleware');

const options = {
    router: function (req) {
       return "http://INVALID";
    }
};

app.use('/test', createProxyMiddleware (options));

app.listen(3000, () => {
  console.log(`Example app listening at http://localhost:3000`)
})

Then :

• npm install
• node test.js
• curl http://localhost:3000/test

Result : following runtime error is logged :

TypeError: Cannot read property 'host' of undefined
    at ProxyServer.HttpProxyMiddleware.logError (C:\Users\dtoch\work\projects\pga\pga-iaf\iaf-hil-common-server-node\node_modules\.pnpm\http-proxy-middleware@1.1.1_debug@4.3.1\node_modules\http-proxy-middleware\dist\http-proxy-middleware.js:141:87)
    at ProxyServer.emit (C:\Users\dtoch\work\projects\pga\pga-iaf\iaf-hil-common-server-node\node_modules\.pnpm\eventemitter3@4.0.7\node_modules\eventemitter3\index.js:210:27)
    at ClientRequest.proxyError (C:\Users\dtoch\work\projects\pga\pga-iaf\iaf-hil-common-server-node\node_modules\.pnpm\http-proxy@1.18.1_debug@4.3.1\node_modules\http-proxy\lib\http-proxy\passes\web-incoming.js:165:18)

Expected behavior

Not a TypeError runtime error should be generated but instead a normal error just indicating that the backend URL is invalid.

Actual behavior

TypeError: Cannot read property ‘host’ of undefined

Workaround

According to https://github.com/chimurai/http-proxy-middleware/pull/512 part of http-proxy-middleware@1.1.1 it should not be needed to define target if using router. However to avoid above error, it is still needed to set it to something e.g. XXX.

Setup

See above.

client info

• node 12.20.2
• npm 7.9.0

target server info

target not defined (only using router section in options).

[dtoch]

Thanks. I confirm the issue doesn’t appear with the new stable release http-proxy-middleware@1.1.2.

[dtoch]

I confirm the issue doesn’t appear with http-proxy-middleware@1.1.2-alpha.1.