Executing a findandmodify with the new:true option set causes exception to be thrown.

Steps to repro:

1. Add document to collection "TestPeople"

2. Call FindAndModify with $set operator & true to return new document {query:

,update:{$set:{"FirstName":"Tim"}},new:true}
3. Verify update has been done

I've also included a screenshot of my console repro of the issue.