- Setting up the environment, dealing with dependency hell, upstream dependencies assuming everyone is using $OS or $ARCH or $FRAMEWORK - Dealing with document

- Setting up the environment, dealing with dependency hell, upstream dependencies assuming everyone is using $OS or $ARCH or $FRAMEWORK - Dealing with documentation that lies to you - Trying to understand and modify code written by people who didn't give a damn to whoever was going to read it some years later -- and resisting the urge to refactor the problematic bits because it would risk the schedule