QueryResult.js

import { NotFoundError } from './errors';

export default class QueryResult {
  constructor(p = Promise.resolve()) {
    this.promise = p;
  }

  null() {
    return new this.constructor((async () => {
      try {
        return await this.promise;
      } catch (err) {
        if (err instanceof NotFoundError) return null;
        throw err;
      }
    })());
  }

  then(...args) {
    return this.promise.then(...args);
  }
}