It worked !
This is what I do :
- Installed node@7.8.0, ionic@3.12.0 and cordova@7.0.1.
- Removed the project folder
- Cloned again
- Directly in package.json set
"cordova-android": "6.4.0" - Then
npm install && ionic cordova build androidand it works !
Also ionic cordova run android --prod works.
Thank you very much @reedrichards and @vibinflogesoft