TypeScript client returns a string instead of the body on error

Having an API which returns a body with errors when the server side validation fails returns just a string instead of the body with the specified error type.

I receive the following message when binding to the error handler: Error Code: 400, Message: Http failure response for https://localhost/api/Delegation: 400 OK

This is the generated code in the client:

createDelegation(model: DelegationModel): Observable<void> {
    let url_ = this.baseUrl + "/api/Delegation";
    url_ = url_.replace(/[?&]$/, "");

    const content_ = JSON.stringify(model);

    let options_ : any = {
        body: content_,
        observe: "response",
        responseType: "blob",
        headers: new HttpHeaders({
            "Content-Type": "application/json",
        })
    };

    return this.http.request("post", url_, options_).pipe(_observableMergeMap((response_ : any) => {
        return this.processCreateDelegation(response_);
    })).pipe(_observableCatch((response_: any) => {
        if (response_ instanceof HttpResponseBase) {
            try {
                return this.processCreateDelegation(<any>response_);
            } catch (e) {
                return <Observable<void>><any>_observableThrow(e);
            }
        } else
            return <Observable<void>><any>_observableThrow(response_);
    }));
}

protected processCreateDelegation(response: HttpResponseBase): Observable<void> {
    const status = response.status;
    const responseBlob =
        response instanceof HttpResponse ? response.body :
        (<any>response).error instanceof Blob ? (<any>response).error : undefined;

    let _headers: any = {}; if (response.headers) { for (let key of response.headers.keys()) { _headers[key] = response.headers.get(key); }}
    if (status === 400) {
        return blobToText(responseBlob).pipe(_observableMergeMap(_responseText => {
        let result400: any = null;
        let resultData400 = _responseText === "" ? null : JSON.parse(_responseText, this.jsonParseReviver);
        result400 = ProblemDetails.fromJS(resultData400);
        return throwException("A server side error occurred.", status, _responseText, _headers, result400);
        }));
    } else if (status === 403) {
        return blobToText(responseBlob).pipe(_observableMergeMap(_responseText => {
        return throwException("A server side error occurred.", status, _responseText, _headers);
        }));
    } else if (status === 200) {
        return blobToText(responseBlob).pipe(_observableMergeMap(_responseText => {
        return _observableOf<void>(<any>null);
        }));
    } else if (status !== 200 && status !== 204) {
        return blobToText(responseBlob).pipe(_observableMergeMap(_responseText => {
        return throwException("An unexpected server error occurred.", status, _responseText, _headers);
        }));
    }
    return _observableOf<void>(<any>null);
}

This is how I bind to the response:

this.delegationClient.createDelegation(model).subscribe(
  () => {
    // result
  },
  error => {
    console.log("error", error);
  }
);

The actual result from the server:

{
   "errors":{
      "UserId":[
         "The field UserId is invalid."
      ]
   },
   "type":"https://tools.ietf.org/html/rfc7231#section-6.5.1",
   "title":"One or more validation errors occurred.",
   "status":400,
   "traceId":"|10d16c7b-492a67427ec0a3ef."
}

The response_ is already the mentioned string instead of type HttpResponseBase with the ProblemDetails in the body. Am I doing something incorrect here or is this a limitation/bug of NSwag?

[curcas]

@RicoSuter I found the problem. It has nothing to do with the library/generated code but with an HttpInterceptor which did this.

[curcas]

I’m using 13.7.0 to generate the spec and the angular (10.x) code.