Handle unknown subscription notification received

src/messages/message-mediator.ts

@@ -121,6 +121,7 @@ export class MessageMediator {
   }
 
   ack(ack: ClientMessageAck) {
+    this.logger.debug("Queuing ack", ack);
     this.ackQueue.push(ack);
   }
 

src/subscription-handler.spec.ts

@@ -67,11 +67,14 @@ describe("SubscriptionManager", () => {
 
     it("gets a subscription", () => {
       const subscription = manager.get(channelID);
+      if (!subscription) {
+        fail("Subscription not found");
+      }
       expect(subscription["endpoint"].toString()).toEqual(endpoint);
     });
 
-    it("throws when subscription is not found", () => {
-      expect(() => manager.get(newUuid())).toThrow("Subscription not found");
+    it("is null when subscription is not found", () => {
+      expect(manager.get(newUuid())).toBeNull();
     });
   });
 

src/subscription-handler.ts

@@ -55,12 +55,9 @@ export class SubscriptionHandler {
     return [...this.subscriptions.keys()];
   }
 
-  get(channelID: Uuid) {
+  get(channelID: Uuid): GenericPushSubscription | null {
     const sub = this.subscriptions.get(channelID);
-    if (!sub) {
-      throw new Error("Subscription not found");
-    }
-    return sub;
+    return sub ?? null;
   }
 
   getByApplicationServerKey(applicationServerKey: string): GenericPushSubscription | undefined {