package.json in trackler-2.1.0.30

- old
+ new

@@ -9,10 +9,11 @@
     "url": "https://github.com/exercism/xecmascript"
   },
   "devDependencies": {
     "babel-jest": "^20.0.1",
     "babel-preset-env": "^1.4.0",
+    "babel-plugin-transform-builtin-extend": "^1.1.2",
     "eslint": "^3.19.0",
     "jest": "^20.0.1"
   },
   "jest": {
     "modulePathIgnorePatterns": [
@@ -20,9 +21,14 @@
     ]
   },
   "babel": {
     "presets": [
       "env"
+    ],
+    "plugins": [
+      ["babel-plugin-transform-builtin-extend", {
+        "globals": ["Error"]
+      }]
     ]
   },
   "scripts": {
     "test": "jest --no-cache ./*",
     "watch": "jest --no-cache --watch ./*",