Property 'forEach' does not exist on type 'Object'

I can't for the life of me figure out why I can't loop over the response from this http call. For whatever reason it's complaining that the type of data is an object, but when I console log it I can an array like I expect.

import { HttpClient, HttpHeaders } from '@angular/common/http';
import { URLSearchParams } from '@angular/http';
import { Observable } from 'rxjs/Observable';
import 'rxjs/add/observable/forkJoin';

promises.push(Observable.create(observer => {
    this.http.post(`items/event/${this.event.auction_code}`, body.toString(), {
        headers: new HttpHeaders().set('Content-Type', 'application/X-www-form-urlencoded' ),
    }).subscribe(data => {
       var classifiedData;
       data.forEach((item)=>{
          classifiedData.push(new Item(item));
       });
       observer.next(data);
       observer.complete();
    },error => {
       observer.throw(error);
    });
}));
...
Observable.forkJoin(promises).subscribe(results => {
   results.forEach((result,i)=>{
      data.content.template[i].data = result;
   });
});

Edit:

Console.log shows me this

Edit: 2

I also have an interceptor setup, could this be causing it?

@Injectable()
export class NoopInterceptor implements HttpInterceptor {
  intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
    const duplicate = req.clone({
      url: `${environment.apiUrl}/${req.url}`,
      params: req.params.set('key', environment.apiKey)
    });
    return next.handle(duplicate);
  }
}