New Twiddle

components.my-component.js

import Ember from 'ember';
import MyMixing from '../utils/my-mixin';

export default Ember.Component.extend(MyMixing, {
});

controllers.application.js

import Ember from 'ember';
import MyMixing from '../utils/my-mixin';

export default Ember.Controller.extend(MyMixing, {
});

templates.application.hbs

{{baseKind}}

{{my-component}}

templates.components.my-component.hbs

{{baseKind}}

twiddle.json

{
  "version": "0.15.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.4.3",
    "ember-template-compiler": "3.4.3",
    "ember-testing": "3.4.3"
  },
  "addons": {
    "ember-data": "3.4.2"
  }
}

utils.my-mixin.js

import Mixin from '@ember/object/mixin';
import Controller from '@ember/controller';
import Component from '@ember/component';
import {computed} from '@ember/object';

export default Mixin.create({
  baseKind: Ember.computed(function() {
    if (this instanceof Controller) {
      return 'Controller';
    } else if (this instanceof Component) {
      return 'Component';
    }
    return 'unknown';
  }),
});