Accessing the `err.stack` property crashes your app under certain circumstances

[balupton]

See winstonjs/winston#401 (comment) for more info

[harishanchu]

Hi foks,

Same issue here.
I have used this library along with nodes "domain" to catch errors. After catching error when I try to access the stack property of error object app crashes and displays's partial error stack which is appended by a string "[object Object]" in the console.

My current Node version is v0.12.0
It worked very well with node v0.10.25.

[mattinsler]

Fixed by PR.