// config.ts

export interface UserConfig {
  // ...
  label?: string
}

export interface Config {
  // ...
  label?: string
}

export function createConfig(config: UserConfig): Config {
  return {
    // ...
    label: config.label
  }
}

// ryu-cho.ts

export const RyuCho {
  // ...

  protected async createIssue(feed: Feed) {
    // ...

    const labels = [this.config.label].filter(v => v);

    const res = await this.github.createIssue(this.upstream, {
      title,
      body,
      labels
    })

    // ...
  }
}

// github.ts

export interface CreateIssueOptions {
  // ...
  labels?: string[]
}

export class GitHub {
  // ...

  createIssue(remote: Remote, options: CreateIssueOptions) {
    return this.api.issues.create({
      owner: remote.owner,
      repo: remote.repo
      title: options.title,
      body: options.body,
      labels: options.labels // added
  }
}