Method start

packages/cli/src/util/dev/server.ts:990–998

(...listenSpec: ListenSpec)

  }

  start(...listenSpec: ListenSpec): Promise<void> {
    if (!this.startPromise) {
      this.startPromise = this._start(...listenSpec).catch(err => {
        this.stop();
        throw err;
      });
    }
    return this.startPromise;
  }

  /**
   * Launches the `vercel dev` server.