This module implicitly depends on process, which isn't defined outside of Node. Prior to a2f87c3, this module had an extra var process = process || {}; in path.js that allowed the use of functions that don't meaningfully rely on process.
And since it sounds like people shouldn't be using this module in Node itself (#6), this problem might affect most legitimate users of this module.
See philc/vimium@da57280 for an example of a legitimate use of this library that was broken by the removal of var process = process || {};.