Received the following error log after terminating an iOS application (signal 9):
[storage] Detected unclean shutdown - /Users/jasonflax/Library/Developer/CoreSimulator/Devices/A8328A47-7C7E-4CB7-A96A-A0DC3D50AFA1/data/Containers/Data/Application/E51E8B25-71B5-4862-833A-CB98B45B0082/mongod.lock is not empty.
It appears that `MongoMobile.close()` was not called as `deinit` is not called when an application is terminated.
This was replicated on an iOS simulator.