title: Property 'catchError' does not exist on type 'Observable<HttpEvent<any>>'
body: <p>Went from angular 5 to 6(using angular 6 &amp; rxjs 6), getting the following two errors in my linter. Anybody have any ideas, please and thank you.</p>
  
  <pre><code>[ts] 'catchError' is declared but its value is never read.
  [ts] Property 'catchError' does not exist on type 'Observable&lt;HttpEvent&lt;any&gt;&gt;'.
  </code></pre>
  
  <pre class="lang-ts prettyprint-override"><code>import { Injectable, Injector } from '@angular/core';
  import { HttpEvent, HttpInterceptor, HttpHandler, HttpRequest } from '@angular/common/http';
  import { catchError } from 'rxjs/operators';
  import { Observable } from 'rxjs';
  
  
  
  @Injectable()
  export class HttpInterceptorService implements HttpInterceptor {
    constructor() { }
  
    intercept(req: HttpRequest&lt;any&gt;, next: HttpHandler): Observable&lt;HttpEvent&lt;any&gt;&gt; {
  
      return next.handle(authReq)
        .catchError((error, caught) =&gt; {
          console.log('Error Occurred');
          console.log(error);
          return Observable.throw(error);
        }) as any;
    }
  }
  </code></pre>