fix(api): add missing 404 check for activities

apps/api/src/app/activities/activities.controller.ts

@@ -301,7 +301,14 @@ export class ActivitiesController {
       id
     });
 
-    if (originalActivity?.userId !== this.request.user.id) {
+    if (!originalActivity) {
+      throw new HttpException(
+        getReasonPhrase(StatusCodes.NOT_FOUND),
+        StatusCodes.NOT_FOUND
+      );
+    }
+
+    if (originalActivity.userId !== this.request.user.id) {
       throw new HttpException(
         getReasonPhrase(StatusCodes.FORBIDDEN),
         StatusCodes.FORBIDDEN