Type 'Observable<{} is not assignable to type 'Observable<HttpEvent<any>>'

Question

I would like to migrate my angular 4 to angular 5. I done the migration from angular 4 to angular 5, and now I have an error on my interceptor to refresh my token. I use this code to intercept all request and refresh my token if I have an 401 error :

import { Observable } from 'rxjs/Observable';
import { Injectable, Injector } from '@angular/core';
import { HttpEvent, HttpInterceptor, HttpHandler, HttpRequest } from '@angular/common/http';
import { UserService } from "./user/services/user.service";
import { SpinnerService } from "angular-spinners";

@Injectable()
export class AngularInterceptor implements HttpInterceptor {
    public userService;
    public spinnerService;

    constructor(private injector: Injector) {
    }

    private applyCredentials = function (req) {
        return req.clone({
            headers: req.headers.set('Authorization', 'Bearer ' + localStorage.getItem('eb-app-token'))
        });
    };

    intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
        this.userService = this.injector.get(UserService);
        this.spinnerService = this.injector.get(SpinnerService);

        return next.handle(this.applyCredentials(req))
            /*.do(event => {

                if (event instanceof HttpResponse) {
                    console.log(event);
                }
            })*/
            .catch((res) => {
                console.log('Token refresh');
                if (res.status === 401 || res.status === 403) {
                    return this.userService.refreshToken().first().flatMap((data: any) => {
                        console.log(data.data);
                        if (data.data !== '') {
                            localStorage.removeItem('token');
                            localStorage.setItem('token', data.data);

                            this.userService.token = localStorage.getItem('token');
                            this.userService.isAuthenticated = true;
                        } else {
                            this.userService.logOut();

                            return Observable.throw(res);
                        }

                        return next.handle(this.applyCredentials(req));
                    });
                }
                else if (res.status === 500) {
                    this.spinnerService.hide('spinner');
                    this.spinnerService.hide('spinner-search');

                    this.userService.logOut();
                }

                return Observable.throw(res);
            });
    }
}

I have this error :

ERROR in src/app/app.interceptor.ts(25,9): error TS2322: Type 'Observable<{} | HttpProgressEvent | HttpSentEvent | HttpHeaderResponse | HttpResponse<any> | Http...' is not assignable to type 'Observable<HttpEvent<any>>'.
  Type '{} | HttpProgressEvent | HttpSentEvent | HttpHeaderResponse | HttpResponse<any> | HttpUserEvent<a...' is not assignable to type 'HttpEvent<any>'.
    Type '{}' is not assignable to type 'HttpEvent<any>'.
      Type '{}' is not assignable to type 'HttpUserEvent<any>'.
        Property 'type' is missing in type '{}'.

I tried to modify different things. I read this post Observable<{}> not assignable to type Observable<SomeType[]> but I don't see the same problem...

The line 25 is :

return next.handle(this.applyCredentials(req))

UPDATE

I modified :

return next.handle(this.applyCredentials(req))

by

return <any>next.handle(this.applyCredentials(req))

and import :

import 'rxjs/add/operator/do';
import 'rxjs/add/operator/catch';

Answer 1

In my case, using Angular 15 app import the interceptor from a library, the error was

Type '(request: HttpRequest, next: HttpHandler) => Observable<HttpEvent>' is not assignable to type '(req: HttpRequest, next: HttpHandler) => Observable<HttpEvent>'. Call signature return types 'Observable<HttpEvent>' and 'Observable<HttpEvent>' are incompatible.

I solved that replace the intercept return from Observable<HttpEvent<any>> to just any.

intercept(request: HttpRequest<unknown>, next: HttpHandler): any {...}

Answer 2

You are not sending an object with the expected type to your handle function. You probably can fix it quickly by parsing it as , like

return next.handle(<any> this.applyCredentials(req))

But you really should check your return types and make sure it meets the expected.

UPDATED Answer: The problem was actually with the function return value, that should be Observable<HttpEvent<any>>. The easy fix would be to cast to any like this

return <any> next.handle(this.applyCredentials(req))

But there is no guarantee that it will work, because it does not belong to the correct class.