null checks on query param sub

src/popup/vault/attachments.component.ts

@@ -26,7 +26,9 @@ export class AttachmentsComponent extends BaseAttachmentsComponent {
         const queryParamsSub = this.route.queryParams.subscribe(async (params) => {
             this.cipherId = params.cipherId;
             await super.ngOnInit();
-            queryParamsSub.unsubscribe();
+            if (queryParamsSub != null) {
+                queryParamsSub.unsubscribe();
+            }
         });
     }