TypeScript:错误TS2322:类型{}不能分配给类型“…”

我有一个接口:

export default interface ValidationResult {
  valid: boolean
  errors?: string[]
}

以及返回实现该接口的对象的函数:

  static validateTitle(title: string): ValidationResult {
    if (title == null || title === '')
      return {valid: false, errors: ["Title can't be empty."]}

    return {valid: true}
  }

但当我试图在另一个函数中使用第一个函数时:

static async validateMovie(title: string): Promise<ValidationResult> {
    const result = this.validateTitle(title)
    if (result.valid === false)
      return new Promise((resolve, reject) => { resolve(result) })
    // other validations...
}

我收到一个TypeScript错误:

error TS2322: Type '{}' is not assignable to type 'ValidationResult'.
  Property 'valid' is missing in type '{}'.

25       return new Promise((resolve, reject) => { resolve(result) })
         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

我试着用 as ValidationResult 到处都是但没有成功。怎么了?我不明白TypeScript在抱怨什么。