fix(Hooks): Fix corner case where ngOnDestroy is called on prototype not instance

Author: zak-cloudnc

projects/ngx-observable-lifecycle/src/lib/ngx-observable-lifecycle.spec.ts

@@ -84,5 +84,27 @@ describe('ngx-observable-lifecycle', () => {
 
       (instance as OnDestroy).ngOnDestroy();
     });
+
+    it('should not throw if onDestroy was invoked on difference instances', () => {
+      const originalOnDestroySpy = jasmine.createSpy();
+
+      class TestClass implements OnDestroy {
+        public ngOnDestroy(): void {
+          originalOnDestroySpy();
+        }
+      }
+
+      const instance = new TestClass();
+      const instance2 = new TestClass();
+
+      const { ngOnDestroy } = getObservableLifecycle(instance);
+
+      expect(originalOnDestroySpy).not.toHaveBeenCalled();
+
+      instance.ngOnDestroy();
+      instance2.ngOnDestroy();
+
+      expect(originalOnDestroySpy).toHaveBeenCalled();
+    });
   });
 });

projects/ngx-observable-lifecycle/src/lib/ngx-observable-lifecycle.ts

@@ -57,7 +57,7 @@ function getSubjectForHook(componentInstance: PatchedComponentInstance<any>, hoo
 
     proto[hook] = function (this: PatchedComponentInstance<typeof hook>) {
       (originalHook as () => void)?.call(this);
-      this[hookSubject][hook].next();
+      this[hookSubject]?.[hook]?.next();
     };
 
     const originalOnDestroy = proto.ngOnDestroy;