anticipate firefox throwing a SecurityError from sw.register()

and just proceed as if they were not supported

src/platform/web/Platform.js

@@ -100,8 +100,10 @@ export class Platform {
         this.onlineStatus = new OnlineStatus();
         this._serviceWorkerHandler = null;
         if (config.serviceWorker && "serviceWorker" in navigator) {
-            this._serviceWorkerHandler = new ServiceWorkerHandler();
-            this._serviceWorkerHandler.registerAndStart(config.serviceWorker);
+            const serviceWorkerHandler = new ServiceWorkerHandler();
+            if (serviceWorkerHandler.registerAndStart(config.serviceWorker)) {
+                this._serviceWorkerHandler = serviceWorkerHandler;
+            }
         }
         this.notificationService = new NotificationService(this._serviceWorkerHandler, config.push);
         this.crypto = new Crypto(cryptoExtras);

src/platform/web/dom/ServiceWorkerHandler.js

@@ -34,10 +34,19 @@ export class ServiceWorkerHandler {
     }
 
     registerAndStart(path) {
-        this._registrationPromise = (async () => {
         navigator.serviceWorker.addEventListener("message", this);
         navigator.serviceWorker.addEventListener("controllerchange", this);
-            this._registration = await navigator.serviceWorker.register(path);
+        let registrationPromise;
+        try {
+            // this can throw a SecurityError in Firefox with hardened settings
+            registrationPromise = navigator.serviceWorker.register(path);
+        } catch (err) {
+            navigator.serviceWorker.removeEventListener("message", this);
+            navigator.serviceWorker.removeEventListener("controllerchange", this);
+            return false;
+        }
+        this._registrationPromise = (async () => {
+            this._registration = await registrationPromise;
             await navigator.serviceWorker.ready;
             this._currentController = navigator.serviceWorker.controller;
             this._registration.addEventListener("updatefound", this);
@@ -48,6 +57,7 @@ export class ServiceWorkerHandler {
             }
             console.log("Service Worker registered");
         })();
+        return true;
     }
 
     _onMessage(event) {