The reason for this error was that another instance of React packager (still on 0.28) was running in the background at the time after I updated to 0.30.
Restarting React packager solved the problem.
The reason for this error was that another instance of React packager (still on 0.28) was running in the background at the time after I updated to 0.30.
Restarting React packager solved the problem.