FAILURE: Build failed with an exception. * What went wrong: A problem occurred configuring project ':app'. > Could not resolve all dependencies for configuration ':app:_debugApk'. > Configuration with name 'default' not found. * Try: Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. BUILD FAILED Total time: 5.383 secs Could not install the app on the device, read the error above for details. Make sure you have an Android emulator running or a device connected and have set up your Android development environment: https://facebook.github.io/react-native/docs/android-setup.html
のようなエラーが出た時には、
- package-lock.jsonを削除する
- npm installする
といいようです。