Angular 5 to 6 Upgrade: Property ‘map’ does not exist on type Observable

Operator chaining has been transitioned to the use of .pipe() in RXJS v6, you should follow the recommended migration path for RXJS. Additionally, the catch operator has been renamed to catchError.

Here is how it should be done now:

const request = this.evidenceService.get().pipe(
    map((res) => res.data)),
    catchError(error => Observable.of(null))
  );