Web server sometimes leaves the port used

Fixes #280

src/main.ts

@@ -97,17 +97,30 @@ async function startup(): Promise<void> {
   }
 }
 
-async function hotLoadSettings(path: string) {
-  log.info("Main", `${path} change detected, reloading.`);
-
+/**
+ * Shuts down all registered file system watchers and the web server
+ */
+async function shutdown(): Promise<void> {
   // Shut down things that are running
   await TriggerManager.stopWatching();
   WebServer.stopApp();
+}
+
+/**
+ * Shuts everything down and then restarts the service with a new settings file.
+ * @param path The path to the settings file that changed.
+ */
+async function hotLoadSettings(path: string) {
+  log.info("Main", `${path} change detected, reloading.`);
 
-  // Start it all back up again
+  await shutdown();
   await startup();
 }
 
+/**
+ * Reloads the list of triggers.
+ * @param path The path to the trigger file that changed.
+ */
 async function hotLoadTriggers(path: string) {
   log.info("Main", `${path} change detected, reloading.`);
 
@@ -142,7 +155,22 @@ function startWatching(): void {
   }
 }
 
-async function main() {
+async function handleDeath(): Promise<void> {
+  log.info("Main", "Shutting down.");
+  await shutdown();
+  process.exit();
+}
+
+function registerForDeath(): void {
+  process.on("SIGINT", handleDeath);
+  process.on("SIGTERM", handleDeath);
+  process.on("SIGQUIT", handleDeath);
+  process.on("SIGBREAK", handleDeath);
+}
+
+async function main(): Promise<void> {
+  registerForDeath();
+
   await startup();
 
   startWatching();