fix systeminformation thread not ending (#4155)

This was introduced when running systeminformation in an own thread.

If the main thread ends before (e.g. when config has errors) the
systeminformation thread never ends.

As this can have side effects under pm2 or docker (because the app never
exits) this PR restores the old behavior.

js/app.js

@@ -328,6 +328,20 @@ function App () {
 		await this.stop();
 		process.exit(0);
 	});
+
+	/**
+	 *
+	 * @param {number} ms milliseconds to wait
+	 */
+	function blockingSleep (ms) {
+		const int32 = new Int32Array(new SharedArrayBuffer(4));
+		Atomics.wait(int32, 0, 0, ms);
+	}
+
+	process.on("exit", () => {
+		// wait before exiting so that child processes (e.g. systeminformation) have some additional time
+		blockingSleep(1000);
+	});
 }
 
 module.exports = new App();