Snyk is flagging Angular’s navigateByUrl() as a potential open redirect vulnerability despite sanitizing the URL

While working on an Angular project, Snyk is flagging the use of navigateByUrl() in one of my functions as a potential open redirect vulnerability.

Despite implementing sanitization and validation, the issue persists. Here’s the function I’m using:

getDocs() {
  this._service.getDocs(this.docID).subscribe(res => {
    if (res) {

      const sanitizedDocID = this.sanitizedDocID(this.docID);

      if (res.lstDocs.length) {

        const redirectUrl = `doc/${sanitizedDocID}`;
        if (this.isValidRedirectUrl(redirectUrl)) {
          this._router.navigateByUrl(redirectUrl);
        }

      } else if (!res.lstDocs.length && res.ListNewDocs.length) {

        const redirectUrl = `new-doc/${sanitizedDocID}`;
        if (this.isValidRedirectUrl(redirectUrl)) {
          this._router.navigateByUrl(redirectUrl);
        }

      } else {
        this._router.navigateByUrl('dashboard');
      }
    }
  });
}

isValidRedirectUrl(url) {
  const trustedUrls = ['doc', 'new-doc'];
  return trustedUrls.indexOf(url) > -1;
}

sanitizedDocID(docId) {
  return docId.replace(/[^0-9]/g, '');
}

Snyk is flagging the navigateByUrl(redirectUrl) calls in this function, despite sanitizing the docID and validating the URLs using isValidRedirectUrl().

What else can be done to resolve this? Kindly assist.