Summary:
This is for issue #7670. I consider this a typo, but maybe you don't.
In order to see the problem, you need to have the packager search for the configuration in a place that doesn't have one and the default configuration can't be provided. It's likely that no one is doing this and also why this probably wasn't seen.
Closes https://github.com/facebook/react-native/pull/7671
Differential Revision: D3350412
fbshipit-source-id: 5f9b520f7d5cbc749e2b898e7bbf2cd84d81ace0