Is it possible to handle BrokenPipe errors?

There doesn’t seem to be a way to handle BrokenPipe errors thrown in std/http/server.ts for individual requests from oak without modifying the Application class. The error occurs if the HTTP client closes the connection prematurely.

Here is an example.

import { Application, Router } from "https://deno.land/x/oak/mod.ts";

console.log("Starting...");

const router = new Router();
const veryLong = "foo bar baz qux ".repeat(1000000);

router.get("/demo", async ctx => {
  ctx.response.type = "text/html; charset=utf-8";
  ctx.response.body = `<h1>Hello!</h1>\n${veryLong}`;
});

const app = new Application();
app
  .use(router.routes())
  .use(router.allowedMethods())
  .listen("localhost:8080");

Save the code above as demo.ts and run the following shell commands to reproduce the error.

> deno --version
deno 0.31.0
v8 8.1.108
typescript 3.7.2
> deno --allow-net demo.ts &
> Compile file:///home/dbohdan/demo.ts
Starting...
> curl http://localhost:8080/demo & sleep 0.1; killall curl
> error: Uncaught BrokenPipe: Broken pipe (os error 32)   
► $deno$/dispatch_minimal.ts:59:11
    at DenoError ($deno$/errors.ts:20:5)
    at unwrapResponse ($deno$/dispatch_minimal.ts:59:11)
    at sendAsyncMinimal ($deno$/dispatch_minimal.ts:102:10)
fish: Job 2, “curl http://localhost:8080/demo…” terminated by signal SIGTERM (Polite quit request)
Job 1, 'deno --allow-net demo.ts &' has ended

[kitsonk]

I believe that already works @hayd. I don’t have a test for it I think but should.

[hayd]

Catching this type of error in the middleware wouldn’t work upon reflection, as the response is being sent, which is after all the middleware ran.

What about other types of error, for example some user thrown Error. Would it be possible to catch this? I was imagining something like this in the middleware:

try { await next() } catch (err) { /* render pretty error page */ }

Upon reflection, I can see it wouldn’t be as easy as that / that won’t work. But that was the usecase I was imaging…