added debug support

Author: Ben Gowers

.vscode/launch.json

@@ -0,0 +1,17 @@
+{
+  // Use IntelliSense to learn about possible attributes.
+  // Hover to view descriptions of existing attributes.
+  // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+  "version": "0.2.0",
+  "configurations": [
+    {
+      "name": "Attach",
+      "port": 9229,
+      "request": "attach",
+      "skipFiles": ["<node_internals>/**"],
+      "type": "node",
+      "sourceMaps": true,
+      "outFiles": ["${workspaceFolder}/lib/**/*.js"]
+    }
+  ]
+}

package.json

@@ -30,8 +30,10 @@
   },
   "scripts": {
     "build": "babel ./src --out-dir lib",
+    "build-maps": "babel ./src --out-dir lib --source-maps",
     "dev": "babel ./src --out-dir lib --watch",
     "start": "node ./lib/index.js",
+    "debug": "node --nolazy --inspect-brk=9229 ./lib/index.js",
     "lint": "eslint ./src",
     "fix": "yarn lint --fix",
     "test": "yarn lint",