Fix #64 prompting error

[yokomotod]

This can fix issues #64.

It seems that first argument of done() expects error object, and second one expects return value.

[yokomotod]

I think I could find the cause of this error.

At 20 hours ago, yeoman-environment upgraded to use inquirer v1.0.0, https://github.com/yeoman/environment/releases/tag/v1.6.0 and inquirer v1.0.0 has changed some its interfaces.

According to the README: https://github.com/SBoudrias/Inquirer.js/compare/v0.12.0...v1.0.0#diff-04c6e90faac2675aa89e2176d2eec7d8R115

{
  /* Preferred way: with promise */
  filter: function () {
    return new Promise(/* etc... */);
  },

  /* Legacy way: with this.async */
  validate: function (input) {
    // Declare function as asynchronous, and save the done callback
    var done = this.async();

    // Do async stuff
    setTimeout(function () {
      if (typeof input !== 'number') {
        // Pass the return value in the done callback
        done('You need to provide a number');
        return;
      }
      // Pass the return value in the done callback
 -    done(true);
 +    done(null, true);
    }, 3000);
  }
}

[technicalpickles]

Thank you for digging into this! It's a pain that yeoman-environment changing it's inquirer dependency causes downstream breakage 😓 I'm not sure there's anything we can do for existing generator-hubot aside from releasing an update with this.

I'm going to review and test, and hopefully get this out soon.

[technicalpickles]

I wonder if we could check the arity of done, ie if (done.length == 2).

[technicalpickles]

Tested and this works ✨ We can leave a potential backwards compat fix ie checking arity of done, and get this out so new users don't have a bad times 😓

[technicalpickles]

This is released in generator-hubot@0.4.0. Anyone running into this should npm install -g generator-hubot to get the latest.