optional-function.js

import Ember from 'ember';

export function optionalFunction(orderedArgs/*, namedArgs*/) {
  const actionFn = orderedArgs[0];
  return function (event) {
    return actionFn ? actionFn(event) : undefined;
  };
}
export default Ember.Helper.helper(optionalFunction);

some-template.hbs

{{some-component some-action=(action (optional-function attrs.someFunc))}}