Handle SIGHUP gracefully

Invoke shutdown instead of exiting immediately when SIGHUP is received,
and do the same on both slave and master for signals received.

packages/master/master.js

@@ -1985,13 +1985,9 @@ async function startServer(args) {
 		logger.info("Caught termination signal, shutting down");
 		shutdown();
 	});
-
-	// terminal closed
 	process.on("SIGHUP", () => {
-		// No graceful cleanup, no warning out (stdout is likely closed.)
-		// Don't close the terminal with the clusterio master in it.
-		// eslint-disable-next-line no-process-exit
-		process.exit(1);
+		logger.info("Terminal closed, shutting down");
+		shutdown();
 	});
 
 	await fs.ensureDir(masterConfig.get("master.database_directory"));

packages/slave/slave.js

@@ -1633,7 +1633,7 @@ async function startSlave() {
 	process.on("SIGTERM", () => {
 		if (secondSigterm) {
 			setBlocking(true);
-			logger.fatal("Caught second termination signal, terminating immediately");
+			logger.fatal("Caught second termination, terminating immediately");
 			// eslint-disable-next-line no-process-exit
 			process.exit(1);
 		}
@@ -1642,6 +1642,10 @@ async function startSlave() {
 		logger.info("Caught termination signal, shutting down");
 		slave.shutdown();
 	});
+	process.on("SIGHUP", () => {
+		logger.info("Terminal closed, shutting down");
+		slave.shutdown();
+	});
 
 	slaveConnector.once("connect", () => {
 		logger.add(new libLoggingUtils.LinkTransport({ link: slave }));