How do I prevent paramMap without pageId to trigger in Angular Modal?

Question

I am using some standard code with paramMap to detect a pageId. When no pageId is detected the app routes you back to home. However when I open this page in a modal of course there is no pageId. Is there a way to detect that the page was opened in a modal and thus no navigation to home is performed? the pageId is still needed for navigation.

    this.route.paramMap.subscribe((paramMap) => {
      if (!paramMap.has('pageId')) {
        this.navCtrl.navigateBack('/home');
        return;
      }
      this.extractedPage = Number(this.route.snapshot.paramMap.get('pageId'));
      if (this.pageWithinBounds(this.extractedPage)) {
        this.activePage = this.extractedPage;
        return;
      }
      this.router.navigate(['/home']);

    });
  }