tumblr/tumblr.js — pull request #6 by adrianseeley (2013-08-04 13:02:06+00:00)
Title: Every 1000-2000 Calls Yields a Malformed Response

Error thrown:
```
TypeError: Cannot read property 'response' of undefined
at Request._callback (T260Gtumblr/node_modules/tumblr.js/lib/tumblr.js:243:31)
at Request.self.callback (T260Gtumblr/node_modules/tumblr.js/node_modules/request/main.js:122:22)
at Request.EventEmitter.emit (events.js:98:17)
at Request. (T260Gtumblr/node_modules/tumblr.js/node_modules/request/main.js:661:16)
at Request.EventEmitter.emit (events.js:117:20)
at IncomingMessage. (T260Gtumblr/node_modules/tumblr.js/node_modules/request/main.js:623:14)
at IncomingMessage.EventEmitter.emit (events.js:117:20)
at _stream_readable.js:910:16
at process._tickCallback (node.js:415:13)
```

This patch ensures the body has a `response`, and calls back with:
```JavaScript
new Error('API error: malformed API response (no response on line)')
```
Rather than crashing the instance.