:bug: INT-1196: null pointer exception
:bug: INT-1196: null pointer exception

```
Bugsnag:  TypeError: Cannot convert undefined or null to object
  at Function.keys (native)
  at new NativeSampler
(/Users/lucas/mongodb/scope-server/node_modules/mongodb-collection-sampl
e/lib/native-sampler.js:22:14)
  at
/Users/lucas/mongodb/scope-server/node_modules/mongodb-collection-sample
/lib/index.js:34:23
  at
/Users/lucas/mongodb/scope-server/node_modules/get-mongodb-version/index
.js:66:5
  at
/Users/lucas/mongodb/scope-server/node_modules/mongodb/lib/admin.js:125:
5
  at handleCallback
(/Users/lucas/mongodb/scope-server/node_modules/mongodb/lib/utils.js:96:
12)
  at
/Users/lucas/mongodb/scope-server/node_modules/mongodb/lib/db.js:922:5
  at commandCallback
(/Users/lucas/mongodb/scope-server/node_modules/mongodb-core/lib/topolog
ies/server.js:936:9)
  at Callbacks.emit
(/Users/lucas/mongodb/scope-server/node_modules/mongodb-core/lib/topolog
ies/server.js:116:3)
  at null.messageHandler
(/Users/lucas/mongodb/scope-server/node_modules/mongodb-core/lib/topolog
ies/server.js:282:23)
  at Socket.<anonymous>
(/Users/lucas/mongodb/scope-server/node_modules/mongodb-core/lib/connect
ion/connection.js:273:22)
  at emitOne (events.js:77:13)
  at Socket.emit (events.js:169:7)
  at readableAddChunk (_stream_readable.js:146:16)
  at Socket.Readable.push (_stream_readable.js:110:10)
  at TCP.onread (net.js:523:20)
```

mongodb-js/mongodb-collection-sample,mongodb-js/collection-sample