I think it is only fair, that a program checking other files for correctness should apply these same standards to itself as well ;-)
I added top level *.js files to the list of files to check for target "lint" and also fixed the issues uncovered by this.
let make.js lint itself
fix make.js lint: use uncoerced comparison
fix make.js lint: declare globals of shelljs
fix make.js lint: declare output function only once
Thanks! Looks good to me. I will squash merge later today.