Hope to help save someone some time by posting this error and solution. I got this error when upgrading React Native, specifically to React Native v0.19.0. It looks like I wasn’t the only one having this problem according to this GitHub issue #5684. So the solution is to use the React Native CLI and run:
I have been manually updating the version of React Native so I didn’t even realize this was a thing. I ran the command and it fixed everything. I definitely need to remember and take advantage of this next time I need to upgrade my version of React Native (I should mention that there’s a new v0.20.0-rc release).