Server crashes trying to get user info when not logged in

[sfiquet]

events.js:183
      throw er; // Unhandled 'error' event
      ^

TypeError: Cannot read property '_id' of undefined
    at /Users/sylvie/Dev/Chingu/BitHelper/routes/users/users.js:57:24
    at model.Query.<anonymous> (/Users/sylvie/Dev/Chingu/BitHelper/node_modules/mongoose/lib/model.js:4056:16)
    at /Users/sylvie/Dev/Chingu/BitHelper/node_modules/kareem/index.js:273:21
    at /Users/sylvie/Dev/Chingu/BitHelper/node_modules/kareem/index.js:131:16
    at _combinedTickCallback (internal/process/next_tick.js:131:7)
    at process._tickCallback (internal/process/next_tick.js:180:9)

It looks like it's accessing req.user._id without checking that req.user is defined.

[sfiquet]

Note: I fixed it in my branch