gistfile1.txt

// Don't do

  return next(req).pipe(
    catchError(error => {
      const status = error.status;
      if (status === HttpStatusCode.BadRequest) {
        // ...
      } else {
        ...
      }
      throwError(() => error);
    })
  ))
  
// Rather do

  return next(req).pipe(
    tap({
      error: error => {
        const status = error.status;
        if (status === HttpStatusCode.BadRequest) {
          // ...
        } else {
          ...
        }
      }
    })
  ))