Summary: I was getting the following error when running `testAsyncStorageTest`
```
uncaught exception 'NSInvalidArgumentException', reason: 'Invalid type in JSON write (NSError)'
```
nicklockwood pointed out that it might be because we're attempting to send a `NSError *` over the bridge at some point. So I went looking for cases where that might happen and found this instance.
public
Reviewed By: jingc
Differential Revision: D2619240
fb-gh-sync-id: dc26ec268f976fec44f2804831398d3b01ab6115