ember-concurrency: Explicitly register Babel plugin

Author: Turbo87

ember-cli-build.js

@@ -27,6 +27,7 @@ module.exports = function (defaults) {
     babel: {
       plugins: [
         require.resolve('ember-auto-import/babel-plugin'),
+        require.resolve('ember-concurrency/async-arrow-task-transform'),
         ...require('ember-cli-code-coverage').buildBabelPlugin({ embroider: true }),
       ],
     },