Return values and not void|values from catch method

I’m using a service for making all webrequest like that:

@Injectable({
  providedIn: 'root'
})
export class WebService {

  auth_token: string;

  constructor(public config: ConfigService, public http: HttpClient, public router: Router) {
    // load token
    this.auth_token = localStorage.getItem("token") ? localStorage.getItem("token") as string : "";
  }

  public async get<T>(dir: string) {
    return await this.http.get<T>(this.config.config.backend.url + dir, { headers: { 'Authorization': `Bearer ${this.auth_token}`, 'Content-Type': 'charset=UTF-8' } }).toPromise();
  }
}

Then, in component, I’m doing like:

constructor(web: WebService) {
   web.get<MyObject[]>("obj").then(values => {
     for(let obj of values) {
        obj.doSomething();
     }
   });
}

I want to manage error more globally, to don’t have to duplicate code. It’s mostly to prevent wrong token/expired token/etc.

So, I edited my service to have like this:

public async get<T>(dir: string) {
   return await this.http.get<T>(this.config.config.backend.url + dir, { headers: { 'Authorization': `Bearer ${this.auth_token}`, 'Content-Type': 'charset=UTF-8' } }).toPromise().catch(err => {
      // here manage all err status code
   });
}

But the catch method return Promise<void | T> and not Promise<T>. So, I have error on the then() method because the values variable can be void. Exact error is: Type 'void | MyObject[]' is not assignable to type 'MyObject[]'.

How can I fix it ?

>Solution :

Return a value in the catch. That can be an empty array for example, when getting a list.

.catch(err => {
  // here manage all err status code
  return [];
}

However, you need to define beforehand in that case, if the default value for the Promise is an empty array, an empty string, zero or whatever