fix(sync): guard against parser errors in UDP message listener

[buffcode]

Summary

• Wrap NtpPacketParser.parse() inside the dgram "message" listener in a try/catch so a parse failure rejects the pending promise cleanly instead of escaping the callback.
• No dependency bump: ntp-packet-parser stays at ^0.5.0. This is the consumer-side guard, landed independently ahead of the parser's input-validation change.
• On parse failure the listener now sets hasFinished = true and calls reject(err), preserving the existing invariants around hasFinished, timeoutHandler, and client.close().

Context

An upcoming ntp-packet-parser release will add input validation to NtpPacketParser.parse() — it will throw TypeError on non-48-byte inputs or non-Buffer arguments. Without this guard, that throw would escape the dgram listener callback and surface as uncaughtException on the Node process. Worse, because the listener is the only path that clears timeoutHandler / sets hasFinished, the outer promise would hang until replyTimeout fires — and on Node processes without a global uncaughtException handler, the process would crash outright.

With this guard, a malformed UDP response produces a rejected promise that the existing retry loop in collectSamples already handles (it catches via .catch((e) => e) and filters Error results out of ntpResults).

Test plan

There are no existing tests in this repo, so yarn build (tsc) is the only automated gate, and it passes.

Manual repro against a local UDP server that returns a malformed response:

const dgram = require("dgram");
const server = dgram.createSocket("udp4");
server.on("message", (_, rinfo) =>
  server.send(Buffer.from("short"), rinfo.port, rinfo.address));
server.bind(1234);
// Then call new NtpTimeSync({...}).getTime() pointed at 127.0.0.1:1234.
// Before: uncaughtException + promise hang. After: promise rejects cleanly.

Note

This PR intentionally does NOT bump the ntp-packet-parser dependency. The parser-side change (input validation) will land in a separate release; this consumer-side guard is defensive and safe to ship first.

🤖 Generated with Claude Code