Class 'HttpClientBackendService' incorrectly implements interface 'HttpBackend'.

[IgorMinar]

When compiling angular.io examples after update to rxjs v6 I'm getting the following error:

node_modules/angular-in-memory-web-api/http-client-backend.service.d.ts(32,22): error TS2420: Class 'HttpClientBackendService' incorrectly implements interface 'HttpBackend'.
  Types of property 'handle' are incompatible.
    Type '(req: HttpRequest<any>) => Observable<HttpResponse<any>>' is not assignable to type '(req: HttpRequest<any>) => Observable<HttpEvent<any>>'.
      Type 'Observable<HttpResponse<any>>' is not assignable to type 'Observable<HttpEvent<any>>'.
        Property 'source' is protected but type 'Observable<T>' is not a class derived from 'Observable<T>'.

I haven't investigated why this error is surfaced only now, but it does seem that the interface is incorrectly implemented. See:

in-memory-web-api/src/in-mem/http-client-backend.service.ts

Line 64 in 7488918

handle(req: HttpRequest<any>): Observable<HttpResponse<any>> {

Which returns an Observable<HttpResponse<any>> and not it's super class Observable<HttpEvent<any>>.

Found in version: 0.5.3

Workaround: disable typecheck of 3rd party code by setting "skipLibCheck": true in tsconfig.json.

[wardbell]

Fixing in addendum to PR #182