fix(api): gracefully handle aborted requests

When a client closes a connection early (e.g. while `await request.text()` is parsing), it throws a `DOMException` with `name: "AbortError"`. Previously, this hit our catch block, was logged as an unhandled exception to the console via `console.error`, and returned a `500` status. This resulted in an alarming error message which looked like a server crash, but the server actually stayed up.

This commit updates `errorResponse` in `src/api.ts` to intercept `AbortError` and handle it properly. If we detect an `AbortError`, we now log a simple `499 Client Closed Request` instead, without writing out the `DOMException` stack trace.

src/api.ts

@@ -15,7 +15,7 @@ function errorResponse(error: unknown): Response {
   }
 
   if (error instanceof Error && error.name === "AbortError") {
-    return json({ ok: false, error: "Request aborted" }, { status: 400 });
+    return json({ ok: false, error: "Request aborted" }, { status: 499 });
   }
 
   console.error(error);