Log synchronous throws from handleUdp handlers

The listener runs from the socket callback, so a non-async handler that
threw before returning a promise reached the unhandled error handler and
took down the host.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/host/src/server.ts

@@ -771,9 +771,14 @@ export class FactorioServer extends events.EventEmitter<FactorioServerEvents> {
 	}
 
 	handleUdp(channel: string, handler: (data: Buffer) => Promise<void>) {
-		this.on(`udp-${channel}`, (data) => handler(data).catch((err: Error) => {
-			this._logger.error(`Error handling udp event:\n${err.stack ?? err.message}`);
-		}));
+		// Runs from the socket callback, so synchronous throws must be caught here too
+		this.on(`udp-${channel}`, async (data) => {
+			try {
+				await handler(data);
+			} catch (err: any) {
+				this._logger.error(`Error handling udp event:\n${err.stack ?? err.message}`);
+			}
+		});
 	}
 
 	async _handleIpc(line: Buffer) {

test/host/server.js

@@ -471,6 +471,20 @@ describe("host/server", function() {
 				assert.equal(lines.length, 1);
 				assert(lines[0].startsWith("Error handling udp event:\nError: boom"), lines[0]);
 			});
+			it("should log errors thrown synchronously by handleUdp handlers", async function() {
+				await server._startUdp();
+				server.handleUdp("sync", () => { throw new Error("sync boom"); });
+				const { lines, restore } = captureLogger("error");
+				try {
+					sendFromGame("sync?data");
+					while (lines.length < 1) {
+						await wait(1);
+					}
+				} finally {
+					restore();
+				}
+				assert(lines[0].startsWith("Error handling udp event:\nError: sync boom"), lines[0]);
+			});
 			it("should forward socket errors", async function() {
 				await server._startUdp();
 				let waiter = events.once(server, "error");