Eu tento executar o aplicativo react-native no emulador android genymotion no meu mac. Quando escrevoreact-native run-android Fica

Running /usr/local/opt/android-sdk/platform-tools/adb reverse tcp:8081 tcp:8081
error: closed
Could not run adb reverse: Command failed: /usr/local/opt/android-sdk/platform-tools/adb reverse tcp:8081 tcp:8081
Building and installing the app on the device (cd android && ./gradlew installDebug...
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
MacBook-Pro-MacBook:ART-CarefulPeople macbook$ 

Então eu tentei:

O mesmo resultado.

Então eu tentei:

react-native bundle --entry-file index.android.js --platform android --bundle-output android/app/src/main/assets/index.android.bundle

curl "http://localhost:8081/index.android.bundle?platform=android" -o "android/app/src/main/assets/index.android.bundle"

react-native run-android

O mesmo resultado.

Eu tentei apenasadb reverse tcp:8081 tcp:8081 e dizerror: closed

Quando tento executar o aplicativo no emulador android-sdk, obtém o mesmo erro acima, mas semerror: closed.

No android studio, eu posso executar este aplicativo e ele funciona em genymotion. Diga-me o que devo fazer para executar meu aplicativo no emulador do Android?