left-pad was a package to, you guessed it, pad a string with n leading characters. Personally, I've always just written my own 2 line function for it (something like `function pad(s, n, ch) { return new Array(n - s.length).fill(ch).join("") + s; }`), but a bunch of packages either directly or indirectly depended on this left-pad package, so they all broke.