TypeError: Cannot call method 'replace' of undefined

When the hook is triggered the following error occurred and the build is not triggered:

```
./jekyll-hook.js
connect deprecated urlencoded.verify: use body-parser module for verify node_modules/express/node_modules/connect/lib/middleware/bodyParser.js:55:21
connect deprecated multipart: use parser (multiparty, busboy, formidable) npm module instead node_modules/express/node_modules/connect/lib/middleware/bodyParser.js:56:20
connect deprecated limit: Restrict request size at location of read node_modules/express/node_modules/connect/lib/middleware/multipart.js:86:15
connect deprecated json.verify: use body-parser module for verify node_modules/express/node_modules/connect/lib/middleware/bodyParser.js:57:15
Listening on port 8080
TypeError: Cannot call method 'replace' of undefined
at /opt/jekyll-hook/jekyll-hook.js:52:32
at pop (/opt/jekyll-hook/node_modules/queue-async/queue.js:24:14)
at Object.q.defer (/opt/jekyll-hook/node_modules/queue-async/queue.js:55:11)
at port (/opt/jekyll-hook/jekyll-hook.js:45:11)
at callbacks (/opt/jekyll-hook/node_modules/express/lib/router/index.js:164:37)
at param (/opt/jekyll-hook/node_modules/express/lib/router/index.js:138:11)
at pass (/opt/jekyll-hook/node_modules/express/lib/router/index.js:145:5)
at Router._dispatch (/opt/jekyll-hook/node_modules/express/lib/router/index.js:173:5)
at Object.router (/opt/jekyll-hook/node_modules/express/lib/router/index.js:33:10)
at next (/opt/jekyll-hook/node_modules/express/node_modules/connect/lib/proto.js:174:15)
```
- NodeJS v0.10.38