Fix TypeScript compilation

Currently this is clearly suboptimal, once we learn more about TS in our projects. We can revisit ember-cli-typescript (or similar) to handle this for us automatically. Additionally, we plan embroider v2 to enable this “for free”

Author: stefanpenner

index.js

@@ -2,4 +2,18 @@
 
 module.exports = {
   name: require('./package').name,
+
+  treeForAddon(tree) {
+    if (this.isDevelopingAddon()) {
+      const {
+        BroccoliBabelPresetTypeScript,
+      } = require('broccoli-babel-preset-typescript'); // eslint-disable-line node/no-unpublished-require
+      return this._super.treeForAddon.call(
+        this,
+        new BroccoliBabelPresetTypeScript([tree])
+      );
+    } else {
+      return this._super.treeForAddon.call(this, tree);
+    }
+  },
 };