Difficulty with passThruUnknownUrl about in-memory-web-api HOT 4 CLOSED

protected handleRequest(req: Request): Observable<Response> {
  const {base, collectionName, id, resourceUrl, query} = this.parseUrl(req.url);
  // collectionName doesn't match anything in the db because it is an external endpoint
  // so `collection` is null
  const collection = this.db[collectionName];
  const reqInfo: RequestInfo = {
    req: req,
    base: base,
    collection: collection,
    collectionName: collectionName,
    headers: new Headers({ 'Content-Type': 'application/json' }),
    id: this.parseId(collection, id),  // pass null collection
    query: query,
    resourceUrl: resourceUrl
  };
}

protected parseId(collection: {id: any}[], id: string): any {
  if (!id) { return null; }
  const isNumberId =  collection[0] && typeof collection[0].id === 'number';  // ERROR!
  if (isNumberId) {
    const idNum = parseFloat(id);
    return isNaN(idNum) ? id : idNum;
  }
  return id;
}

protected parseId(collection: {id: any}[], id: string): any {
  if (!collection || !id) { return null; }

} else if (this.inMemDbService[reqMethodName]) {
  const interceptorArgs: HttpMethodInterceptorArgs = {
    requestInfo: reqInfo,
    db: this.db,
    config: this.config,
    passThruBackend: this.passThruBackend
  };
  return this.inMemDbService[reqMethodName](interceptorArgs);
} else if (reqInfo.collection) {
  return this.collectionHandler(reqInfo);
} else if (this.passThruBackend) {
  return this.passThruBackend.createConnection(req).response;
}

} else if (this.inMemDbService[reqMethodName] && reqInfo.collection) {