Setting up build tools always sucks copious amounts of ass.
I tend to explore new languages, and I tend to start a lot of projects that I abandon at 20%. This means I spend a spend a lot of time trying to set everything up so that builds work on all the platforms, tests and lints run, deployments, etc.
And its the worst! So many different build tools and module systems etc, and so many of them are the worst. More than once I've just been like "fuck this, I shouldn't have to read a book to target two platforms - I'm making a .sh file in 15 min that just does all the steps".