Crash after websocket connection is made

[TheNicolasDeveloper]

Checks

• I understand project setup issues should be asked on StackOverflow or in GitHub Discussions.
• I updated to latest http-proxy-middleware.

Describe the bug (be clear and concise)

When I attempt to connect to a proxied websocket, it crashes

The error:

TypeError: undefined is not an object (evaluating 'server.on')
      at C:\projects\Nova\services\Nova.Backend\node_modules\http-proxy-middleware\dist\http-proxy-middleware.js:56:17
      at C:\projects\Nova\services\Nova.Backend\node_modules\http-proxy-middleware\dist\http-proxy-middleware.js:50:22

Step-by-step reproduction instructions

1. Add a proxy middleware with ws set to true
2. Make a request to a websocket
3. Crash

Expected behavior (be clear and concise)

It should not crash upon a websocket request

How is http-proxy-middleware used in your project?

const frontendProxyMiddleware = createProxyMiddleware({
    target: "http://localhost:3000",
    changeOrigin: true,
    ws: true,
});

app.use(
    frontendProxyMiddleware
);

What http-proxy-middleware configuration are you using?

{
    target: "http://localhost:3000",
    changeOrigin: true,
    ws: true,
}

What OS/version and node/version are you seeing the problem?

System:
    OS: Windows 11 10.0.26100
    CPU: (16) x64 AMD Ryzen 7 7700X 8-Core Processor
    Memory: 15.11 GB / 31.15 GB
  Binaries:
    Node: 22.12.0 - C:\Program Files\nodejs\node.EXE
    npm: 10.9.0 - C:\Program Files\nodejs\npm.CMD
    bun: 1.1.42 - ~\.bun\bin\bun.EXE
  Utilities:
    Git: 2.47.1.
    Curl: 8.10.1 - C:\WINDOWS\system32\curl.EXE
  IDEs:
    VSCode: 1.96.2 - C:\Users\Nicolas\AppData\Local\Programs\Microsoft VS Code\bin\code.CMD
    Visual Studio: 17.12.35527.113 (Visual Studio Community 2022)
  Languages:
    Java: 21.0.5
  Browsers:
    Edge: Chromium (131.0.2903.112)

Additional context (optional)

No response