This problem is caused by the the Arduino IDE not fully removing the previous hardware package version when you updated to a new version via Boards Manager. It is solved by completely removing the old package version:
- Open /Users/alessandrobarbiero/Library/Arduino15/packages/esp8266/hardware/esp8266
- You will now see multiple version subfolders. One of these folders is the one you upgraded from that was not fully removed. Delete that folder. Please be very careful when deleting files on your computer, when in doubt back up!
After that the compilation error will be fixed.