Error when attempting to write to a null socket

A user has reported this error crashing the server.

file:///usr/local/lib/node_modules/postgres/src/connection.js:255
      const x = socket.write(chunk, fn)
                       ^
  TypeError: Cannot read properties of null (reading 'write')
      at Immediate.nextWrite (file:///usr/local/lib/node_modules/@rocicorp/zero/node_modules/postgres/src/connection.js:255:22)
      at process.processImmediate (node:internal/timers:485:21)
      at process.callbackTrampoline (node:internal/async_hooks:130:17)
  Node.js v22.15.0

This appears to point to this line of code: https://github.com/porsager/postgres/blob/5c8135f3df1bb10e7aad10f14a6f084db3724f82/src/connection.js#L255

The only other helpful information from our logs is the fact that the server was heavily loaded and requests to other services were timing out.

Is this a known issue and is there anything we can do to investigate how this happens (or how to prevent it)?

Start in src/connection.js around line 255 and trace how the socket can be null when nextWrite runs. Use the reported stack trace and the heavy-load and timeout details to identify reproducible conditions. Done means explaining the failure path and documenting or testing a reliable prevention, if the investigation supports one.