TypeError in Neon Serverless Connector: Cannot Read Properties of Null (Reading 'send')

[rkacenski]

Steps to reproduce

1. Set up a Cloudflare Worker using the @neondatabase/serverless library.
2. Create a route handler that establishes a connection to a Neon PostgreSQL database but doesn’t always run queries.
3. Close the connection using client.end() after the route handler completes.
4. Trigger the route. If no data is sent over the connection, the error occurs.

Expected result

The connection should close gracefully, even if no data is sent over the WebSocket.

Actual result

The following error is thrown:

Uncaught TypeError: Cannot read properties of null (reading 'send')

It happens when the WebSocket connection is closed before buffered data can be sent.

Environment

• Library: @neondatabase/serverless v0.5.7
• Runtime: Cloudflare Workers
• Database: Neon PostgreSQL
• Framework: Custom framework with Drizzle ORM and Neon connector

Logs, links

Relevant error log:

✘ [ERROR] Uncaught TypeError: Cannot read properties of null (reading 'send')
(file:///path/to/@neondatabase/serverless/index.js:1003:65)

Code snippet where the issue occurs:

serverless/shims/net/index.ts

Line 504 in da779b2

this.ws!.send(this.writeBuffer!);

setTimeout(() => {
  this.ws!.send(this.writeBuffer!); // error here
  this.writeBuffer = undefined;
}, 0);

Potential Fix

  setTimeout(() => {
     if (this.ws) {
       this.ws.send(this.writeBuffer!);
     } else {
       // Handle the case where the websocket is closed
       console.warn('WebSocket is closed before write could occur');
     }
     this.writeBuffer = undefined;
   }, 0);

[jawj]

Thanks for opening an issue. I'll take a look at this.

[rkacenski]

@jawj What do you think of my PR?

[jawj]

Sorry @rkacenski, I will get to this, but it may take another week or two.

[rkacenski]

@jawj Coming up on 2 months since I opened this. Is this covered in the recent refactor? When can we expect this? Thanks

[rkacenski]

Didn't mean to close this sorry

[jawj]

Sorry for the delay. The big refactor is now merged.

I can see how this issue could happen on Cloudflare (where opening a WebSocket is async) if Drizzle is trying to communicate with the DB even before you issue a query. So I've tried to add a test to pick this up, but so far I haven't managed to reproduce it.

Can you provide a minimal reproduction so I can be sure it's addressed?

I'm currently doing this in the request function and it seems there's no problem:

import { drizzle } from 'drizzle-orm/neon-serverless';

const client = new Client({ connectionString: DATABASE_URL });
const db = drizzle(client);
await client.connect();  // same result with or without this

// do nothing

ctx.waitUntil(client.end());  // same result with plain `await`
return new Response('{ "result": "OK" }', { headers: { 'Content-Type': 'application/json' } });