Error when trying to install app with mysql2 gem

Question

Im trying to install an open source rails 3.2.21 application that uses the mysql2 gem, but when i try and run the bundle commant I get the followin

Answer 1

sudo installer -pkg /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg -target /

From here: https://gorails.com/setup/osx/10.14-mojave