серьезно 10.14 уже все?
==> Upgrading mas 1.7.1 -> 1.8.2
mas: A full installation of
Xcode.app 12.0 is required to compile
this software. Installing just the Command Line Tools is not sufficient.
Xcode 12.0 cannot be installed on macOS 10.14.
You must upgrade your version of macOS.
Error: mas: An unsatisfied requirement failed this build.