This piece of code stops my API from throwing "socket hang up" but I have no idea why

[dan-cooke]

app.use(function (req, res, next) {
    req.socket.on('error', (err) => console.error(err));
    next();
  });

Thats it.

The weirdest part?

The console.error never even gets hit, so i have no idea why the socket error is happening.

But when I put this code in, the socket errors stop happening, its like Schrodinger's socket.

Does anyone know why the hell this is happening? I would prefer to not have some magic, nonsensical piece of code in my server.

Tested on the following docker images
node:18-bullseye-slim
node:18.3-bullseye-slim

Additional info
I am usig the following libraries to serve a GraphQL API

 apollo-server-core: 3.6.3
 apollo-server-express: 3.6.3
 express: 4.18.1
 mongodb: 4.4.1
 mongoose: 6.2.4

[dan-cooke]

Okay so I will probably never understand why this is happening, its something to do with fly.io - every other deployment seems to work, with even just whitespace changes.

Switching to Cloudflare