解析器github仓库

Question

使用RxJS编写程序以按术语搜索github存储库。 错误：类型Observable<string | Repositories>无法分配给类型Observable<string | ResponseModel>。如何解决此错误？

interface ResponseModel {
  count: number;
  items: Repositories[];
};
interface Repositories {
  title: string;
};
const searchField: HTMLInputElement  = document.querySelector('.search-field') as HTMLInputElement;
const repositories: HTMLUListElement = document.querySelector('.repositories') as HTMLUListElement;
const sequence$ = fromEvent(searchField, 'input');
const clearResult = ():void => {
  if (repositories) {
    repositories.innerHTML = '';
  }
};
const sequence2$: Observable<string | ResponseModel> = sequence$
  .pipe(
    debounceTime(300),
    distinctUntilChanged(),
    tap(clearResult),
    switchMap((event: KeyboardEvent) => request(event)
      .pipe(catchError(error => of('Error: ${'Not found'}')))
    )
  );
sequence2$.subscribe(result => showRepo(result));
function request(event: KeyboardEvent): Observable<Repositories> {
  const url: string = `${'https://api.github.com/search/repositories'}?q=${(event.target as  HTMLInputElement).value}`;
    return from(fetch(url).then(res => res.json()));
};
function showRepo(res: ResponseModel) {...}
}

    <input class="search-field" type="text">
    <ul class="repositories"></ul>