New Twiddle

components.inner-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  actions: {
    bar() {
      if(this.foo) {
        this.foo(...arguments);
      }
    }
  }
});

components.outer-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  actions: {
    foo() {
      alert('clicked');
    }
  }
});

templates.application.hbs

{{outer-component}}

templates.components.inner-component.hbs

<button onclick={{action 'bar'}}>
	{{yield}}
</button>

templates.components.outer-component.hbs

{{#inner-component foo=(action 'foo')}}With action{{/inner-component}}
{{#inner-component}}Without action{{/inner-component}}

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"
  }
}